Metal alloys for the reflective or the semi-reflective layer of an optical storage medium

ABSTRACT

A silver-based alloy thin film is provided for the highly reflective or the semi-reflective layer of optical discs. Alloy additions to silver include gold, rhodium, ruthenium, osmium, platinum, palladium, copper, silicon, cadmium, tin, lithium, nickel, cobalt, manganese, indium, chromium, antimony, gallium, boron, molybdenum, zirconium, beryllium, titanium, aluminum, germanium and zinc. These alloys have moderate to high reflectivity and reasonable corrosion resistance in ambient environments.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This patent application is a continuation-in-part of patentapplication Ser. No. 10/457,935 filed Jun. 10, 2003 which is acontinuation-in-part of application Ser. No. 10/342,649, filed Jan. 15,2003, which is a continuation-in-part of application Ser. No.10/090,855, filed Mar. 4, 2002, which is a continuation-in-part ofapplication Ser. No. 09/661,062, filed Sep. 13, 2000, now U.S. Pat. No.6,451,402, issued on Sep. 17, 2002, which is a continuation-in-part ofapplication Ser. No. 09/557,135, filed Apr. 25, 2000, which is acontinuation-in-part of application Ser. No. 09/438,864, filed Nov. 12,1999, now U.S. Pat. No. 6,280,811, issued on Aug. 28, 2001, which is acontinuation-in-part of application Ser. No. 09/102,163, filed Jun. 22,1998, now U.S. Pat. No. 6,007,889, issued on Oct. 28, 1999, and is alsoa continuation-in-part of application Ser. No. 10/409,037, filed on Apr.8, 2003, which is a continuation of application Ser. No. 09/834,775filed on Apr. 13, 2001, now U.S. Pat. No. 6,544,616, issued on Apr. 8,2003, which claims the benefit of U.S. Provisional Application No.60/219,843.

FIELD OF THE INVENTION

[0002] This invention relates to reflective layers or semi-reflectivelayers used in optical storage media that are made of silver-basedalloys.

BACKGROUND OF THE INVENTION

[0003] Four layers are generally present in the construction of aconventional, prerecorded, optical disc such as compact audio disc. Afirst layer is usually made from optical grade, polycarbonate resin.This layer is manufactured by well-known techniques that usually beginby injection or compression molding the resin into a disc. The surfaceof the disc is molded or stamped with extremely small and preciselylocated pits and lands. These pits and lands have a predetermined sizeand, as explained below, are ultimately the vehicles for storinginformation on the disc.

[0004] After stamping, an optically reflective layer is placed over theinformation pits and lands. The reflective layer is usually made ofaluminum or an aluminum alloy and is typically between about 40 to about100 nanometers (nm) thick. The reflective layer is usually deposited byone of many well-known vapor deposition techniques such as sputtering orthermal evaporation. Kirk-Othmer, Encyclopedia of Chemical Technology,3^(rd) ed. Vol. 10, pp. 247 to 283, offers a detailed explanation ofthese and other deposition techniques such as glow discharge, ionplating, and chemical vapor deposition, and this specification herebyincorporates that disclosure by reference.

[0005] Next, a solvent-based or an UV (ultraviolet) curing-type resin isapplied over the reflective layer, which is usually followed by a label.The third layer protects the reflective layer from handling and theambient environment. And the label identifies the particular informationthat is stored on the disc, and sometimes, may include artwork.

[0006] The information pits residing between the polycarbonate resin andthe reflective layer usually take the form of a continuous spiral. Thespiral typically begins at an inside radius and ends at an outsideradius. The distance between any 2 spirals is called the “track pitch”and is usually about 1.6 microns for compact audio disc. The length ofone pit or land in the direction of the track is from about 0.9 to about3.3 microns. All of these details are commonly known for compact audiodiscs and reside in a series of specifications that were first proposedby Philips NV of Holland and Sony of Japan as standards for theindustry.

[0007] The disc is read by pointing a laser beam through the opticalgrade polycarbonate substrate and onto the reflective layer withsufficiently small resolution to focus on the information pits. The pitshave a depth of about ¼ of the wavelength of the laser light, and thelight generally has a wavelength in the range of about 780 to 820nanometers. Destructive (dark) or constructive (bright) interference ofthe laser light is then produced as the laser travels along the spiraltrack, focusing on an alternating stream of pits and lands in its path.

[0008] This on and off change of light intensity from dark to bright orfrom bright to dark forms the basis of a digital data stream of 1 and0's. When there is no light intensity change in a fixed time interval,the digital signal is “0,”and when there is light intensity change fromeither dark to bright or bright to dark, the digital signal is “1.” Thecontinuous stream of ones and zeros that results is then electronicallydecoded and presented in a format that is meaningful to the user such asmusic or computer programming data.

[0009] As a result, it is important to have a highly reflective coatingon the disc to reflect the laser light from the disc and onto a detectorin order to read the presence of an intensity change. In general, thereflective layer is usually aluminum, copper, silver, or gold, all ofwhich have a high optical reflectivity of more than 80 percent from 650nm to 820 nm wavelength. Aluminum and aluminum alloys are commonly usedbecause they have a comparatively lower cost, adequate corrosionresistance, and are easily placed onto the polycarbonate disc.

[0010] Occasionally and usually for cosmetic reason, a gold or copperbased alloy is used to offer the consumer a “gold” colored disc.Although gold naturally offers a rich color and satisfies all thefunctional requirements of a highly reflective layer, it iscomparatively much more expensive than aluminum. Therefore, acopper-based alloy that contains zinc or tin is sometimes used toproduce the gold colored layer. But unfortunately, the exchange is nottruly satisfactory because the copper alloy's corrosion resistance, ingeneral, is considered worse than aluminum, which results in a disc thathas a shorter life span than one with an aluminum reflective layer.

[0011] For the convenience of the reader, additional details in themanufacture and operation of an optically readable storage system can befound in U.S. Pat. Nos. 4,998,239 to Strandjord et al. and 4,709,363 toDirks et al., the disclosures of which are hereby incorporated byreference.

[0012] Another type of disc in the compact disc family that has becomepopular is the recordable compact disc or “CD-R.” This disc is similarto the CD described earlier, but it has a few changes. The recordablecompact disc begins with a continuous spiral groove instead of acontinuous spiral of pits and has a layer of organic dye between thepolycarbonate substrate and the reflective layer. The disc is recordedby periodically focusing a laser beam into the grooves as the lasertravels along the spiral track. The laser heats the dye to a hightemperature, which in turn places pits in the groove that coincide withan input data stream of ones and zeros by periodically deforming anddecomposing the dye.

[0013] For the convenience of the reader, additional details regardingthe operation and construction of these recordable discs can be found inU.S. Pat. Nos. 5,325,351 to Uchiyama et al., and 5,391,462; 5,415,914;and 5,419,939 to Arioka et al., and 5,620,767 to Harigaya et al., thedisclosures of which are hereby incorporated into this specification byreference.

[0014] The key component of a CD-R disc is the organic dye, which ismade from solvent and one or more organic compounds from the cyanine,phthalocyanine or azo family. The disc is normally produced by spincoating the dye onto the disc and sputtering the reflective layer overthe dye after the dye is sufficiently dry. But because the dye maycontain halogen ions or other chemicals that can corrode the reflectivelayer, many commonly used reflective layer materials such as aluminummay not be suitable to give the CD-R disc a reasonable life span. Sobeing, frequently gold must be used to manufacture a recordable CD. Butwhile gold satisfies all the functional requirements of CD-R discs, itis a very expensive solution.

[0015] Recently, other types of recordable optical disks have beendeveloped. These optical disks use a phase-change or magneto-opticmaterial as the recording medium. An optical laser is used to change thephase or magnetic state (microstructural change) of the recording layerby modulating a beam focused on the recording medium while the medium isrotated to produce microstructural changes in the recording layer.During playback, changes in the intensity of light from the optical beamreflected through the recording medium are sensed by a detector. Thesemodulations in light intensity are due to variations in themicrostructure of the recording medium produced during the recordingprocess. Some phase-change and/or magneto-optic materials may be readilyand repeatedly transformed from a first state to a second state and backagain with substantially no degradation. These materials may be used asthe recording media for a compact disc-rewritable disc, or commonlyknown as CD-RW.

[0016] To record and read information, phase change discs utilize therecording layer's ability to change from a first dark to a second lightphase and back again. Recording on these materials produces a series ofalternating dark and light spots according to digital input dataintroduced as modulations in the recording laser beam. These light anddark spots on the recording medium correspond to 0's and 1's in terms ofdigital data. The digitized data is read using a low laser power focusedalong the track of the disc to play back the recorded information. Thelaser power is low enough such that it does not further change the stateof the recording media but is powerful enough such that the variationsin reflectivity of the recording medium may be easily distinguished by adetector. The recording medium may be erased for re-recording byfocussing a laser of intermediate power on the recording medium. Thisreturns the recording medium layer to its original or erased state. Amore detailed discussion of the recording mechanism of opticallyrecordable media can be found in U.S. Pat. Nos. 5,741,603; 5,498,507;and 5,719,006 assigned to the Sony Corporation, the TDK Corporation, andthe NEC Corporation, all of Tokyo, Japan, respectively, the disclosuresof which are incorporated herein by reference in their entirety.

[0017] Still another type of disc in the optical disc family that hasbecome popular is a prerecorded optical disc called the digitalvideodisc or “DVD.” This disc has two halves. Each half is made ofpolycarbonate resin that has been injection or compression molded withpit information and then sputter coated with a reflective layer, asdescribed earlier. These two halves are then bonded or glued togetherwith an UV curing resin or a hot melt adhesive to form the whole disc.The disc can then be played from both sides as contrasted from thecompact disc or CD where information is usually obtained only from oneside. The size of a DVD is about the same as a CD, but the informationdensity is considerably higher. The track pitch is about 0.7 micron andthe length of the pits and lands is from approximately 0.3 to 1.4microns.

[0018] One variation of the DVD family of discs is the DVD-dual layerdisc. This disc also has two information layers; however, both layersare played back from one side. In this arrangement, the highlyreflectivity layer is usually the same as that previously described. Butthe second layer is only semi-reflective with a reflectivity in therange of approximately 18 to 30 percent at 650 nm wavelength. Inaddition to reflecting light, this second layer must also pass asubstantial amount of light so that the laser beam can reach the highlyreflective layer underneath and then reflect back through thesemi-reflective layer to the signal detector.

[0019] In a continued attempt to increase the storage capacity ofoptical discs, a multi-layer disc can be constructed as indicated in thepublication “SPIE Conference Proceeding Vol. 2890, page 2-9, November,1996” where a tri-layer or a quadri-layer optical disc was revealed. Allthe data layers were played back from one side of the disc using laserlight at 650 nm wavelength. A double-sided tri-layered read-only-discthat included a total of six layers can have a storage capacity of about26 gigabytes of information.

[0020] More recently, a blue light emitting laser diode with wavelengthof 400 nm has been made commercially available. The new laser willenable much denser digital videodisc data storage. While current DVDusing 650 nm red laser can store 4.7 GB per side, the new blue laserwill enable 12 GB per side, enough storage space for about 6 hours ofstandard-resolution video and sound. With a multi-layer disc, there isenough capacity for a featured movie in the high-definition digitalvideo format. Silver alloys of the present invention can be used for anyone layer of the multi-layer optical disc.

[0021] Recent advances in the development of thin silver alloy films foruse as both semi-reflective and highly reflective layers in DVD-9s hasmade it feasible to create tri-layer and even quadruple-layer opticaldiscs with all playback information layers on the same side of the disc.See for example, U.S. Pat. Nos. 6,007,889, and 6,280,811. Thusmultiple-layer disc can be constructed and manufactured at low cost.Combined with objective lens having a numerical aperture (NA) of 0.60,and playback lasers having a wavelength of about 650 nm, multiple-layeroptical storage devices with the capacity to store 14 gigabytes ofinformation (DVD-14) or 18 gigabytes (DVD-18) of information storagecapacity can be made.

[0022] Various formats for the next generation optical discs have beenproposed. One of these is referred to so as a “Blu-ray” disc. TheBlu-ray disc system is characterized by a playback laser operating at awavelength of about 405 nm (blue light) and an objective lens with anumerical aperture of 0.85. The storage capacity of this device, usedwith one information layer, is estimated to be about 25 gigabytes forthe prerecorded format. Such devices have track pitch values in the 0.32μm range and channel bit length on the order of 0.05 μm.

[0023] Because the focal depth of an objective lens with a NA of 0.85 istypically less than one micron, the tolerance of the optical path lengthvariation is drastically reduced relative to currently used systems.Thus a cover layer about 100 microns thick (the distance is measuredfrom the surface of the disc to the information layer) has beenproposed. The variation of the thickness of this cover layer isextremely critical to the success of this system. For example, a 2 or 3micron thickness variation in the cover layer will introduce very highspherical aberration in the playback signal, potentially degrading thesignal to an unacceptable low level.

[0024] Another major problem with the Blu-ray format is that the currentgeneration of production equipment used for DVDs can not be used toproduce discs with the Blu-ray format, because the proposed format istoo different from currently used DVD format. The need to invest in newequipment to manufacture Blu-ray discs substantially increases the costof making the Blu-ray disc, and presents another obstacle to adoptingthe Blu-ray disc system as the standard for the next generation of DVD.

[0025] In part, because of the aforementioned problems associated withthe Blu-ray disc, another format for the next generation of DVD has beenproposed. This proposed format is sometimes referred to as the AdvancedOptical Disc” (AOD).

[0026] The AOD format preserves some of the features of the currentlyused DVD, for example, an AOD comprises two 0.6 mm thick half-discsglued together to create a symmetrical structure. The proposed AODsystem uses a playback laser with a wavelength of 405 nm and anobjective lens with a NA of about 0.65. The storage capacity of theprerecorded type of AOD disc with one information layer is about 15gigabytes. Although manufacturing a AOD disc is less complicated andless challenging than manufacturing a Blu-ray disc, AOD suffers onedrawback. The playback signal quality of an AOD disc is stronglydependant upon the flatness of the disc. In order to deal with thevariation of disc flatness introduced in the mass production of AODdiscs, a tilt servo mechanism in the player is most likely required. Theneed for this mechanism will increase the cost of players designed toread AOD discs.

[0027] Currently, there is an interest in adapting CD-RW techniques tothe DVD field to produce a rewritable DVD (DVD−RW) and next generationphase-change rewritable discs such as Blu-ray or AOD. Some difficultiesin the production of a DVD−RW have arisen due to the higher informationdensity requirements of the DVD format. For example, the reflectivity ofthe reflective layer must be increased relative that of the standard DVDreflective layer to accommodate the reading, writing, and erasingrequirements of the DVD−RW format. Also, the thermal conductivity of thereflective layer must also be increased to adequately dissipate the heatgenerated by both the higher laser power requirements to write and eraseinformation and the microstructural changes occurring during theinformation transfer process. The potential choice of the reflectivelayer is currently pure gold, pure silver and aluminum alloys. Goldseems to have sufficient reflectivity, thermal conductivity, andcorrosion resistance properties to work in a DVD−RW disk. Additionally,gold is relatively easy to sputter into a coating of uniform thickness.But once again, gold is also comparatively more expensive than othermetals, making the DVD−RW format prohibitively expensive. Pure silverhas higher reflectivity and thermal conductivity than gold, but itscorrosion resistance is relatively poor as compared to gold. Aluminumalloy's reflectivity and thermal conductivity is considerably lower thaneither gold or silver, and therefore is not necessarily a good choicefor the reflective layer in DVD−RW or DVD+RW.

[0028] For the convenience of the reader, additional details regardingthe manufacture and construction of DVD discs can be found in U.S. Pat.No. 5,640,382 to Florczak et al. the disclosure of which is herebyincorporated by reference.

[0029] Therefore, what is needed are some new alloys that have theadvantages of gold when used as a reflective layer or as asemi-reflective layer in an optical storage medium, but are not asexpensive as gold. These new alloys also have better corrosionresistance than pure silver. The current invention addresses that need.

SUMMARY OF THE INVENTION

[0030] It is an objective of this invention to provide new metallicalloys for thin film reflective layers that has high reflectivity andsimilar sputtering characteristics as gold, and is corrosion resistantyet inexpensive. When a layer of this invention is made thin enough, itcan be semi-reflective and transmissive to laser light and used inapplications such as a DVD-dual layer.

[0031] It is another objective of this invention to provide a lower costalternative to the gold reflective layer in a recordable compact discand still satisfy other functional requirements of the disc such as,high reflectivity and corrosion resistance.

[0032] It is a further objective of this invention to provide asilver-based alloy with chemical, thermal, and optical properties thatsatisfy the functional requirements of the reflective layer in a DVD−RWor DVD+RW disc, and other current or future generations of optical discsin which reflectivity, corrosion resistance, and ease of application areall important requirements for a low cost and high performance product.

[0033] In one aspect, this invention is an optical storage medium,comprising: a first layer having a pattern of features in at least onemajor surface; and a first coating adjacent the first layer, the firstcoating includes a first metal alloy; wherein the first metal alloycomprises: silver; and at least one other element, selected from thegroup consisting of copper, zinc, silicon, cadmium, tin, lithium,nickel, cobalt, indium, chromium, antimony, gallium, boron, molybdenum,zirconium, beryllium, germanium, aluminum, manganese, and titanium,wherein said other elements are present from 0.01 a/o percent to 10.0a/o percent of the amount of silver present. In another aspect of theinvention, the aforementioned elements alloyed with silver are presentin the amount of 0.1 a/o percent to 5.0 a/o percent. The first coatingof the optical storage medium may directly contact the first metal layerof the medium.

[0034] In another aspect of the invention, the medium may furthercomprise a second layer having a pattern of features in at least onemajor surface and a second coating adjacent to the second layer. Thesecond layer may include a dielectric material. Additionally, the mediummay include a third layer having a pattern of features in at least onemajor surface, the third layer including an optically recordablematerial and a forth layer having a pattern of features in at least onemajor surface, the forth layer may include a dielectric material.

[0035] In another aspect, this invention is an optical storage medium.The optical storage medium has a substrate with a pattern of features inat least one major surface and a recording layer adjacent the featurepattern. A semi-reflective layer then resides adjacent the recordinglayer. The optical storage medium may also have a second substrate witha pattern of features in at least one major surface, a second recordinglayer adjacent the feature pattern, and a second reflective layeradjacent the recording layer. A space layer is then located between thefirst and second substrates. At least one of the reflective orsemi-reflective coatings are made of silver and copper wherein therelationship between the amounts of silver and copper is defined byAg_(x)Cu_(t) where 0.90<x<0.999 and 0.001<t<0.10.

[0036] In still another aspect this invention is an optical storagemedium comprising a first layer having a pattern of features in at leastone major surface and a semi-reflective layer adjacent to the firstfeature pattern. The semi-reflective layer or coating can be comprisedof any of the metal alloys of the invention suitable for use in asemi-reflective layer and compatible for use with a laser in the rangeof 405 nm. The storage medium further includes a second layer having apattern of features in at least one major surface and a highlyreflective layer or coating adjacent to the second pattern of features.In one embodiment of the invention the first pattern of featuresincludes a spiral groove.

[0037] In yet another aspect the invention provides an optical storagedevice including, in addition to a first layer and second layer eachhaving feature patterns, a forth layer including an optically recordablematerial positioned between a third layer including a dielectricmaterial and a fifth layer including a dielectric material. Opticalrecording layer 4 and dielectric layers 3 and 5 are positioned betweenthe first layer and the second layer. In one embodiment of the inventionthe feature pattern in either, or both, the first and second layerscomprise a spiral groove either with or without data pits.

[0038] In one embodiment of the invention the recordable material inlayer 4 is a phase changeable material.

[0039] In still another embodiment of the invention the recordablematerial in layer 4 is magnetic optical recordable material.

[0040] In yet another embodiment of the invention the recordablematerial in layer 4 is a optically active dye.

[0041] In another aspect of the invention, the optically recordablematerial is a phase-changeable material. The optically recordablematerial may comprise a phase changeable materials selected from thegroup consisting of Ge—Sb—Te, As—In—Sb—Te, Cr—Ge—Sb—Te, As—Te—Ge,Te—Ge—Sn, Te—Ge—Sn—O, Te—Se, Sn—Te—Se, Te—Ge—Sn—Au, Ge—Sb—Te, Sb—Te—Se,In—Se—Tl, In Sb, In—Sb—Se, In—Se—Tl—Co, Bi—Ge, Bi—Ge—Sb, Bi—Ge—Te, andSi—Te—Sn. The optically recordable material may be a magneto-opticmaterial selected for example from the group consisting of Tb—Fe—Co andGd—Tb—Fe.

[0042] In another aspect of the invention, the first metal alloy in thea layer of an optical recording medium may comprise copper, zinc, andsilver wherein copper is present from about 0.01 a/o percent to about10.0 a/o percent, zinc is present from about 0.01 a/o percent to 10.0a/o, and the remainder is silver.

[0043] In another aspect of the invention, a metal alloy in a layer ofan optical recording medium may comprise copper, titanium, and silver,wherein copper is present in about 0.01 a/o percent to about 10.0 a/opercent of the amount of silver present, and titanium is present fromabout 0.01 a/o percent to about 5.0 a/o percent of the amount of silverpresent in the alloy.

[0044] In another aspect of the invention, a metal alloy in a layer ofan optical recording medium may comprise silver; and at least one othermetal selected from the group consisting of gold, rhodium, ruthenium,osmium, iridium, platinum, palladium, and mixtures thereof, wherein atleast one of these metals is present from about 0.01 a/o percent toabout 5.0 a/o percent of the amount of silver present.

[0045] In another aspect of the invention, the metal alloy in a layer ofan optical recording medium may comprise silver, copper, and silicon,wherein copper is present from about 0.01 a/o percent to about 10.0 a/opercent of the amount of silver present, and silicon is present fromabout 0.01 a/o percent to about 5.0 a/o percent of the amount of silverpresent.

[0046] In still another aspect this invention is an optical informationrecording medium, comprising: a first substrate having a pattern offeatures in at least one major surface; a first recording layer adjacentthe feature pattern; and a first reflective layer adjacent to the firstrecording layer. The reflective layer includes a first metal alloy;wherein the first metal alloy comprises: silver; and at least one otherelement selected from the group consisting of copper, zinc, titanium,cadmium, lithium, nickel, cobalt, indium, aluminum, germanium, chromium,germanium, tin, beryllium, magnesium, manganese, antimony, gallium,silicon, boron, zirconium, molybdenum, and mixtures thereof, whereinsaid other elements are present from 0.01 a/o percent to 10.0 a/opercent of the amount of silver present. In another aspect of theinvention, the other elements of the aforementioned metal alloy arepresent from about 0.1 a/o percent to 5.0 a/o percent of the amount ofsilver present in the alloy.

[0047] In one aspect of the invention, the first recording layer of anoptical information recording medium may directly contact the firstmetal layer.

[0048] In another aspect of the invention, a metal alloy of an opticalrecording medium, may comprise silver, copper, and zinc wherein copperis present from about 0.01 a/o percent to 10.0 a/o percent of the amountof silver present, and zinc is present from about 0.01 a/o percent to10.0 a/o percent of the amount of silver present.

[0049] In another aspect of the invention, a metal alloy of a layer ofan optical recording medium is comprised of silver and at least oneelement selected from the group consisting of gold, rhodium, ruthenium,osmium, iridium, platinum, palladium, and mixtures thereof, wherein theelement is present from about 0.01 a/o percent to 5.0 a/o percent of theamount of silver present.

[0050] In yet another aspect, the invention is an optical storagemedium, comprising: a first substrate having a pattern of features in atleast one major surface; a semi-reflective layer adjacent a featurepattern, the semi-reflective layer including a metal alloy; the metalalloy comprising: silver; and copper; wherein the relationship betweenthe amounts of silver and copper is defined by Ag_(x)Cu_(y), where0.90<x<0.999, 0.001<y<0.10; a second substrate having a pattern offeatures in at least one major surface; a high reflective layer adjacentthe feature pattern of the second substrate; and at least one spacerlayer, located between said first and second substrates.

[0051] The aforementioned medium may further include a second substratehaving a pattern of features in at least one major surface and a secondreflective layer adjacent the second substrate. The metal alloy may alsobe comprised of at least one additional element selected from the groupconsisting of silicon, cadmium, tin, lithium, nickel, cobalt, indium,chromium, antimony, gallium, boron, molybdenum, zirconium, beryllium,titanium, magnesium, wherein the elements are present from about 0.01a/o percent to 10.0 a/o percent of the amount of silver present.

[0052] In still another aspect of the invention, the first metal alloyin an optical storage medium with both reflective and semi-reflectivelayers, comprising Ag_(x)Cu_(y), where 0.90<x<0.999, 0.001<y<0.10 ,includes manganese present from about 0.01 a/o percent to about 7.5 a/opercent of the amount of silver present.

[0053] In still another aspect of the invention, the metal alloy in anoptical storage medium with both reflective and semi-reflective layers,comprising Ag_(x)Cu_(y), where 0.90<x<0.999, 0.001<y<0.10, includesmanganese present from about 0.01 a/o percent to about 5.0 a/o percentof the amount of silver present.

[0054] In still another aspect of the invention, the metal alloy in anoptical storage medium with both reflective and semi-reflective layers,comprising Ag_(x)Cu_(y), where 0.90<x<0.999, 0.001<y<0.10, includestitanium present from about 0.01 a/o percent to about 5.0 a/o percent ofthe amount of silver present.

[0055] In still another aspect of the invention, the metal alloy in anoptical storage medium with both reflective and semi-reflective layers,comprising Ag_(x)Cu_(y) where 0.90<x<0.999, 0.001<y<0.10, includessilicon present from about 0.01 a/o percent to about 5.0 a/o percent ofthe amount of silver present.

[0056] In another aspect of the invention, the semi-reflective layer ofoptical storage medium includes a metal alloy comprising Ag_(x)Cu_(y),wherein 0.95<x<0.999, 0.001<y<0.050.

[0057] In another aspect of the invention, an optical storage medium hasat least one semi-reflective layer comprising a metal alloy includingAg_(x)Cu_(y), wherein 0.95<x<0.999, 0.001<y<0.050.

[0058] In another aspect of the invention, the semi-reflective layer ofan optical storage medium directly contacts the first metal alloy of themedium.

[0059] In another aspect of the invention, an optical informationrecording medium, may further include a second substrate having apattern of features in at least one major surface and spacer layerlocated between the first and second substrates.

[0060] In one aspect, this invention is an optical storage medium with afirst substrate having a pattern of features in at least one majorsurface and a first reflective layer adjacent the feature pattern. Thereflective layer is made of a silver and zinc alloy wherein therelationship between the amount of silver and the amount of zinc isdefined by Ag_(x)Zn_(y), where 0.85<x<0.9999 and 0.0001<y<0.15.

[0061] In another aspect, this invention is an optical storage mediumwith a first substrate having a pattern of features in at least onemajor surface and a first reflective layer adjacent the feature pattern.The reflective layer is made of a silver and aluminum alloy where therelationship between the amount of silver and the amount of aluminum isdefined by Ag_(x)Al_(z), where 0.95<x<0.9999 and 0.0001<z<0.05.

[0062] In another aspect, this invention is an optical storage mediumwith a first substrate having a pattern of features in at least onemajor surface and a first reflective layer adjacent the feature pattern.The reflective layer is made of a silver and zinc and aluminum alloywhere the relationship between the amount of silver and the amount ofzinc and the amount of aluminum is defined by Ag_(x)Zn_(y)Al_(z), where0.80<x<0.998 and 0.001<y<0.15, and 0.001<z<0.05.

[0063] In another aspect, this invention is an optical storage mediumwith a first substrate having a pattern of features in at least onemajor surface and a first reflective layer adjacent the feature pattern.The reflective layer is made of a silver and manganese alloy where therelationship between the amount of silver and manganese is defined byAg_(x)Mn_(t), where 0.925<x<0.9999 and 0.0001<t<0.075.

[0064] In another aspect, this invention is an optical storage mediumwith a first substrate having a pattern of features in at least onemajor surface and a first reflective layer adjacent the feature pattern.The reflective layer is made of a silver and germanium alloy wherein therelationship between the amount of silver and the amount of germanium isdefined by Ag_(x)Ge_(q), where 0.97<x<0.9999 and 0.0001<q<0.03.

[0065] In another aspect, this invention is an optical storage mediumwith a first substrate having a pattern of features in at least onemajor surface and a first reflective layer adjacent the feature pattern.The reflective layer is made of a silver and copper and manganese alloywherein the relationship between the amount of silver and the amount ofcopper and the amount of manganese is defined by Ag_(x)Cu_(p)Mn_(t),where 0.825<x<0.9998 and 0.0001<p<0.10, and 0.0001<t<0.075.

BRIEF DESCRIPTION OF THE DRAWINGS

[0066]FIG. 1 is an optical storage system according to one embodiment ofthis invention.

[0067]FIG. 2 is an optical storage system according to anotherembodiment of this invention where an organic dye is used as a recordinglayer.

[0068]FIG. 3 is an optical storage system according to anotherembodiment of this invention with two layers of information pits wherethe playback of both layers is from one side.

[0069]FIG. 4 is an optical storage system according to anotherembodiment of this invention with three layers of information pits wherethe playback of all three layers is from one side.

[0070]FIG. 5 is an optical storage system according to anotherembodiment of this invention where the system contains a rewritableinformation layer.

[0071]FIG. 6 is an optical storage system according to anotherembodiment of this invention where the system contains a rewritableinformation layer.

[0072]FIG. 7 is an optical storage system according to anotherembodiment of this invention for example a DVD-14.

[0073]FIG. 8 is an optical storage system according to anotherembodiment of this invention the for example a DVD-18.

[0074]FIG. 9 is an optical storage system according to anotherembodiment of the invention, an optical storage system of the Blu-raytype with layers suitable for high density digital information storagereadable from one side.

[0075]FIG. 10 is an optical storage system according to anotherembodiment of the invention, an optical storage system of the Blu-raytype including two re-writable high density digital information storagelayers readable and re-recordable from one side.

[0076]FIG. 11 is an optical storage system according to anotherembodiment of the invention, an optical storage system of the AdvancedOptical Disc (AOD) type including two high density digital informationstorage layers readable from one side.

[0077]FIG. 12 is an optical storage system according to anotherembodiment of the invention, an optical storage system of the AdvancedOptical Disc (AOD) type including two re-writable high density digitalinformation storage layers readable and re-recordable from one side.

[0078]FIG. 13 is an optical storage system according to still anotherembodiment of the invention including two readable and recordable layersreadable and recordable from one side.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0079] Specific language is used in the following description andexamples to publicly disclose the invention and to convey its principlesto others. No limits on the breadth of the patent rights based simply onusing specific language are intended. Also included are any alterationsand modifications to the descriptions that should normally occur to oneof average skill in this technology.

[0080] As used in this specification the term “atomic percent” or “a/opercent” refers to the ratio of atoms of a particular element or groupof elements to the total number of atoms that are identified to bepresent in a particular alloy. For example, an alloy that is 15 atomicpercent element “A” and 85 atomic percent element “B” could also bereferenced by a formula for that particular alloy: A_(0.15)B_(0.85).

[0081] As used herein the term “of the amount of silver present” is usedto describe the amount of a particular additive that is included in thealloy. Used in this fashion, the term means that the amount of silverpresent, without consideration of the additive, is reduced by the amountof the additive that is present to account for the presence of theadditive in a ratio. For example, if the relationship between Ag and anelement “X” is Ag_(0.85) X_(0.15) (respectively 85 a/o percent and 15a/o percent) without the considering the amount of the additive that ispresent, and if an additive “B” is present at a level 5 atomic percent“of the amount of silver present”; then the relationship between Ag, X,and B is found by subtracting 5 atomic percent from the atomic percentof silver, or the relationship between Ag, X, and B is Ag_(0.80)X_(0.15) B_(0.05) (respectively 80 a/o percent silver, 15 a/o percent“X”, and 5 a/o percent “B”).

[0082] As used in this specification the term “adjacent”refers to aspatial relationship and means “nearby” or “not distant.” Accordingly,the term “adjacent” as used in this specification does not require thatitems so identified are in contact with one another and that they may beseparated by other structures. For example, referring to FIG. 5, layer424 is “adjacent” or “nearby” layer 422, just as layer 414 is “adjacent”or “nearby” layer 422.

[0083] Metal alloys for use in optical recording devices have beendisclosed in U.S. Pat. Nos. 6,007,889, 6,280,811, 6,451,402 B1 and6,544,616 B2, and these patents are hereby incorporated by reference intheir entirety.

[0084] This invention comprises multi-layer metal/substrate compositionsthat are used as optical data storage media. One embodiment of thisinvention is shown in FIG. 1 as optical data storage system 10. Opticalstorage medium 12 comprises a transparent substrate 14, and a highlyreflective thin film layer or coating 20 on a first data pit pattern 19.An optical laser 30 emits an optical beam toward medium 12, as shown inFIG. 1. Light from the optical beam that is reflected by thin film layer20 is sensed by detector 32, which senses modulations in light intensitybased on the presence or absence of a pit or land in a particular spoton the thin film layer. The disc is unique in that one of the alloyspresented below is deposited upon the information pits and lands and isused as the highly reflective thin film 20. In one alternative (notshown), the disc may be varied by attaching two optical storage media 12back-to-back, that is, with each transparent substrate 14 facingoutward.

[0085] Another embodiment of this invention is shown in FIG. 2 asoptical data storage system 110. Optical storage medium 112 comprises atransparent substrate 114, and a highly reflective thin film layer 120,over a layer of dye 122, placed over a first pattern 119. An opticallaser 130 emits an optical beam toward medium 112, as shown in FIG. 2.As discussed earlier, data is placed upon the disc by deforming portionsof the dye layer with a laser. Thereafter, the disc is played by lightfrom the optical beam, which is reflected by thin film layer 120 andsensed by detector 132. Detector 132 senses modulations in lightintensity based on the presence or absence of a deformation in the dyelayer. The disc is unique in that one of the alloys presented below isdeposited over the dye layer 122 and is used as the highly reflectivethin film or coating 120. In one alternative (not shown), the disc maybe varied by attaching two optical storage media 112 back-to-back, thatis, with each transparent substrate 114 facing outward.

[0086] Another embodiment of this invention is shown in FIG. 3 asoptical data storage system 210. Optical storage medium 212 comprises atransparent substrate 214, a partially reflective thin film layer orcoating 216 on a first data pit pattern 215, a transparent spacer layer218, and a highly reflective thin film layer or coating 220 on a seconddata pit pattern 219. An optical laser 230 emits an optical beam towardmedium 212, as shown in FIG. 3. Light from the optical beam that isreflected by either thin film layer 216 or 220 is sensed by detector232, which senses modulations in light intensity based on the presenceor absence of a pit in a particular spot on the thin film layers. Thedisc is unique in that one of the alloys presented below is depositedupon the information pits and lands and used as the highly reflectivethin film 220 or semi-reflective layer 216. In another alternative (notshown), the disc may be varied by attaching two optical storage media212 back-to-back, that is, with each transparent substrate 214 facingoutward. The attachment method could be by UV cured adhesive, hot meltadhesive or other type of adhesives.

[0087] Another embodiment of this invention is shown in FIG. 4 asoptical data storage system 310. Optical storage medium 312 comprises atransparent substrate 314, a partially reflective thin film layer orcoating 316 or layer “zero” on a first data pit pattern 315, atransparent spacer layer 318, another partially reflective thin filmlayer or coating 320 or layer “one” on a second data pit pattern 319, asecond transparent spacer layer 322, and a highly reflective thin filmlayer or coating 324 or layer“two” on a third pit pattern 323. Anoptical laser 330 emits an optical beam toward medium 312, as shown inFIG. 4. Light from the optical beam that is reflected by thin film layer316, 320 or 324 is detected by detector 332, which senses modulation inlight intensity based on the presence or absence of a pit in aparticular spot on the thin film layers. The disc is unique in that anyor all of the alloys presented below can be deposited upon theinformation pits and lands and used as the highly reflective thin filmor coating 324 or the semi-reflective layer or coating 316 and 320. Toplayback the information on Layer 2, the light beam from laser diode 330is going through the transparent polycarbonate substrate, passingthrough the first semi-reflective Layer 0, and the secondsemi-reflective Layer 1 and then reflected back from layer 2 to thedetector 332. In another alternative (not shown), the disc may be variedby attaching two optical storage media 312 back-to-back, that is, witheach transparent substrate 314 facing outward. The attachment methodcould be by UV cured adhesive, hot melt adhesive or other type ofadhesives.

[0088] Still another embodiment of this invention is shown in FIG. 5 asoptical data storage system 410. Optical storage medium 412 comprises atransparent substrate or a transparent layer 414, a dielectric layer 416on a first data pit pattern 415, a recording layer 418 made of amaterial having a microstructure including domains or portions capableof repeatedly undergoing laser-induced transitions from a first state toa second state and back again (i.e., an optically re-recordable orrewritable layer), such as a phase change material or a magneto-opticmaterial, another dielectric material 420, a highly reflective thin filmlayer 422, and a transparent substrate or layer 424. As used in thisspecification, a dielectric material is a material that is an electricalinsulator or in which an electric field can be sustained with a minimumdissipation of power. The different layers 414, 416, 418, 420 and 422 ofthe optical storage medium 410 are preferably oriented so as to beadjacent with one another.

[0089] The optical recordable material may be for example, amagneto-optic material selected from the group consisting of Tb—Fe—Coand Gd—Tb—Fe.

[0090] Commonly used phase change materials for the recording layer 418include germanium-antimony-tellurium (Ge—Sb—Te),silver-indium-antimony-tellurium (Ag—In—Sb—Te),chromium-germanium-antimony-tellurium (Cr—Ge—Sb—Te) and the like.Commonly used materials for the dielectric Layer 416 or 420 include zincsulfide-silica compound (ZnS.SiO₂), silicon nitride (SiN), aluminumnitride (AlN) and the like. Commonly used magneto-optic materials forthe recording layer 418 include terbium-iron-cobalt (Tb—Fe—Co) orgadolinium-terbium-iron (Gd—Tb—Fe). An optical laser 430 emits anoptical beam toward medium 412, as shown in FIG. 5. In the recordingmode for the phase change recordable optical medium, light from theoptical beam is modulated or turned on and off according to the inputdigital data and focused on the recording layer 418 with suitableobjective while the medium is rotated in a suitable speed to effectmicrostructural or phase change in the recording layer. In the playbackmode, the light from the optical beam that is reflected by the thin filmlayer 422 through the medium 412 is sensed by the detector 432, whichsenses modulations in light intensity based on the crystalline oramorphous state of a particular spot in the recording layers. The discis unique in that one of the alloys presented below is deposited uponthe medium and used as the highly reflective thin film 422. In anotheralternative (not shown), the disc may be varied by attaching two opticalstorage media 412 back-to-back, that is, with each transparent substrateor coating 414 facing outward. The attachment method could be by UVcured adhesive, hot melt adhesive or other type of adhesives.

[0091] As shown in FIG. 5, if transparent substrate 414 is about 1.2 mmthick made of injection molded polycarbonate with continuous spirals ofgrooves and lands, 424 is a UV cured acrylic resin 3 to 15 micron thickacting as a protective layer with the playback laser 430 at 780 to 820nanometer, and rewritable layer 418 is a phase change material of atypical composition such as Ag—In—Sb—Te, it is a compact disc-rewritabledisc structure, commonly known as a CD-RW. To record and readinformation, phase change discs utilize the recording layer's ability tochange from an amorphous phase with low reflectivity (dark) to acrystalline phase with high reflectivity (bright). Before recording, thephase change layer is in a crystalline state. During recording, a laserbeam with high power focused on the recording layer will heat the phasechange material to high temperature and when the laser is turned off,the heated spot will cool off very quickly to create an amorphous state.Thus a series of dark spots of amorphous states are created according tothe input data of turning the focused laser beam on and off. These onand off correspond to “0” and “1” of a digital data stream.

[0092] In reading, a low laser power is used to focus on and read thedark or bright spots along the track of the disc to play back therecorded information. To erase, an intermediate laser power is used tofocus on the grooves or tracks with the disc spinning so that anintermediate temperature of the focused spots is reached. After thelaser is moved to another location, the spots cool to room temperatureforming a crystalline structure of high reflectivity. This returns therecording layer to its original or erased state. The change of thespots' state from amorphous to crystalline is very reversible, thus manyrecord and erase cycles can be accomplished and different data can berepeatedly recorded and read back without difficulty.

[0093] If transparent substrate 414 is about 0.5 to 0.6 mm thick made ofinjection molded polycarbonate with continuous spirals of grooves andlands, 416 and 420 are dielectric layers typically made of ZnS.SiO₂, 418is made of a phase change material such as Ag—In—Sb—Te or Ge—Sb—Te, 422is made of a silver alloy of the current invention, and 424 is a UVcured resin bonding another half of the same structure as depicted inFIG. 5., and the structure is used with a read and write laser 430 at630 to 650 nanometer wavelength, then it is a digital versatile discwith rewritable capability, commonly referred to as DVD+RW. Somepreferred phase-changeable materials include materials from thefollowing series: As—Te—Ge, As—In—Sb—Te, Te—Ge—Sn, Te—Ge—Sn—O, Bi—Ge,Bi—Ge—Sb, Bi—Ge—Te, Te—Se, Sn—Te—Se, Te—Ge—Sn—Au, Ge—Sb—Te, Sb—Te—Se,In—Se—Tl, In—Sb, In—Sb—Se, In—Se—Tl—Co, Cr—Ge—Sb—Te and Si—Te—Sn, whereAs is arsenic, Bi is Bismuth, Te is tellurium, Ge is germanium, Sn istin, O is oxygen, Se is selenium, Au is gold, Sb is antimony, In isindium, Tl is thallium, Co is cobalt, and Cr is chromium. In this discconfiguration, the highly reflective layer 422 needs not only highreflectivity at 650 nanometer wavelength and high thermal conductivity,but also high corrosion resistance in the presence of ZnS.SiO₂.Conventional aluminum alloy does not have high enough reflectivity norhigh enough thermal conductivity. Pure silver or other conventionalsilver alloys do not have either high corrosion resistance or highreflectivity and high thermal conductivity. Thus it is another objectiveof the current invention to provide a series of silver alloys that canmeet the requirements for this application.

[0094] Another embodiment of the current invention is shown in FIG. 6, arewritable type optical information storage system 510. Transparentcover layer 514 is approximately 0.1 mm thick. Dielectric layers 516 and520 are preferably made of ZnS.SiO₂ and serve as a protective layer forthe rewritable layer or phase change layer 518. Rewritable layer 518 ispreferably formed from Ag—In—Sb—Te or the like. Highly reflective layer522 is preferably formed from a silver alloy, such as disclosed herein.Transparent substrate 524 is preferably approximately 1.1 mm inthickness with continuous spiral tracks of grooves and lands usuallymade with polycarbonate resin. Laser 530 preferably has a wavelength ofabout 400 nm with associated optics to focus the laser beam ontorecording layer 518. The reflected laser beam is received by thedetector 532, which preferably includes associated data processingcapability to read back the recorded information. System 510 issometimes called a “Digital Video Recording System”or DVR, and it isdesigned to record high definition TV signal. The principle of operationof optical information storage system 510 is similar to that of a CD-RWdisc except that the recording density is considerably higher, thestorage capacity of a 5 inch diameter disc is approximately 20gigabytes. Again the performance of the disc stack depends on a layer522, that is highly reflective at 400 nm wavelength, with high corrosionresistance and very high thermal conductivity. Conventional reflectivelayers such as aluminum, gold or copper all have difficulty meetingthese requirements. Thus it is another objective of the currentinvention to provide a silver alloy reflective layer that is capable ofmeeting these demanding requirements.

[0095] Other optical recording media which can be used to practice thisinvention include for example optical storage devices readable and insome embodiments also rewritable from both sides of the device.

[0096] One embodiment of this invention is illustrated in FIG. 7 opticaldata storage system 610. Optical storage system 610 is sometimesreferred to as DVD-14 and is illustrative of devices that have thecapacity to store accessible data on both sides of the structure.

[0097] Optical storage system 610 comprises a 0.6 mm thick transparentpolycarbonate substrate (PC), adjacent to the PC layer or a part of thePC layer is a first data pit pattern 614 comprising a series of pits andlands. Adjacent to layer 614 and conforming to the contour of layer 614is a semi-reflective layer or coating 618. Adjacent to the layer orcoating 618 is a spacer 622 comprised of a transparent material adjacentto or a part of spacer layer 622 is a second data pit pattern 626comprising a series of pits and lands. Adjacent to and conforming to thecontour of second data pit pattern 626 is a reflective layer or coating630. Both semi-reflective layer or coating 618 and highly reflectivelayers 630 can be read from the same side of structure 610.

[0098] Adjacent to layer or coating 634 is a second reflective layer orcoating 638. Layer or coating 638 is adjacent to and conforms to thecontours of a third data pit pattern 642 comprising a series of pits andlands. Third data pit pattern 642 and highly reflective layer or coating638 are readable from the side of the device opposite to the side of thedevice from which data pit patterns 618, 626 are read. Adjacent to orcomprising data pit pattern 642 is a second 0.6 mm thick polycarbonatelayer.

[0099] An optical laser 660 emits an optical beam towards secondpolycarbonate layer PC, the beam is reflected by highly reflective layeror coating 638 and sensed by detector 662 modulations in light intensitybased on the presence or absence of a pit in a particular spot on thehighly reflective coating or layer.

[0100] As illustrated in FIG. 7, from the side of device 610 opposite oflaser 660, a second optical beam from laser 650 is directed towardsfirst polycarbonate substrate layer PC towards data pit pattern 614. Asillustrated in FIG. 7, the second laser 650 emits an optical beamtowards semi-reflective layer or coating 618 and highly reflective layer630. At least a portion of the optical beam emitted by laser 650 passesthrough semi-reflective layer 618 to reach reflective layer 626. Lightfrom the optical beam that is reflected by layer or coating 626 issensed by detector 652, which senses modulations in light intensitybased on the presence or absence of a pit or land in a particular spoton the highly reflective layer.

[0101] While the optical storage device illustrated in FIG. 7 comprisesmultiple laser sources 650, 660 and multiple detectors 652, 662, thesame could be accomplished using a single laser source and detectorconfigured such that the same optical beam source and detector can beused to collect signal from all sets of information pits and landscomprising the device, for example set 618, 626, 642.

[0102] In still another embodiment the invention may be practiced usingthe optical storage system 710 as illustrated in FIG. 8. Optical storagemedium 710 is illustrative of a DVD-18 and is representative of opticalstorage systems that have multiple information layers readable from bothsides of the optical storage medium.

[0103] Optical storage system 710 comprises a 0.6 mm thick transparentsubstrate 712 adjacent to, or comprising a first data pit pattern 714.Data pit pattern 714 comprises a series of pits and lands and isadjacent to a semi-reflective layer or coating 716. The device furtherincludes a transparent spacer layer 718 about 50 microns thick, and asecond data pit pattern 720 adjacent to a highly reflective film orcoating 722. Both semi-reflective layer or coating 716 and highlyreflective layer or coating 722 can be read from the same side of 710.

[0104] An optical laser 770 emits an optical beam towards transparentlayer 712. As illustrated in FIG. 7 at least a portion of the opticalbeam emitted by laser source 770 passes through semi-reflective layer716 to reach highly reflective layer 722. Light from the optical beamthat is reflected by semi-reflective layer or coating 716 and highlyreflective layer 722 is sensed by detector 772, which senses modulationsin light intensity based on the presence or absence of a pit or land ina particular spot on the highly reflective layer or the semi-reflectivelayer.

[0105] The optical storage device illustrated in FIG. 8 further includesthe spacer layer 724, which connects the portion of the devicecomprising the first two information layers 714, 720 with the portion ofthe device comprising the third and forth information layers 728, 734.Substrate layer 724 is adjacent to and separates highly reflective layeror coating 728 and highly reflective layer or coating 722.

[0106] Highly reflective layer or coating 724 is adjacent to, andconforms to the contours of the pit and lands or data pit pattern layer728. Layer 728 is adjacent to spacer layer 726, spacer layer 726 isadjacent to semi-reflective layer 732, which is adjacent to, andconforms to the contours of data pit pattern layer 734. Data pit patternlayer 734 is contiguous with, or adjacent to, 0.6 mm thick substratelayer 736.

[0107] In the embodiment illustrated in FIG. 8 an optional secondoptical laser 780 is provided which emits an optical beam towards layer736. A portion of the light emitted by laser 780 passes throughsemi-reflective layer or coating 732 and is reflected by highlyreflective layer or coating 724 light reflected by semi-reflective layeror coating 732 and highly reflective layer 724 is sensed by detector782, which senses modulations in light intensity based on the presenceor absence of a pit or land in a particular spot on the highlyreflective layer.

[0108] While the optical storage device illustrated in FIG. 8 includesmultiple laser sources 770, 780 and multiple detectors 752, 772, thesame could be accomplished using a single laser source and detectorconfigured such that the same optical beam source and detector can beused to collect signal from all sets of information pits and landscomprising the device.

[0109] Yet another embodiment of the inventions includes the proposednext generation optical storage device sometimes referred to as“Blu-ray.” Blu-ray devices incorporate lasers, which operate at awavelength of 405 nm and lenses, with a numerical aperture of 0.85.

[0110] As illustrated in FIG. 9 optical storage system 810 of theprerecorded type of “Blu-Ray” disc comprises two sets of informationpits and lands 818 and 830 readable from the same side of the device.Device 810 comprises transparent cover layer 814 about 0.1 mm inthickness, and a substrate layer 838 about 1.1 mm thickness with anadjacent highly reflective layer or coating 834. Highly reflective layeror coating 834 is adjacent to, and conforms to the second data pitpattern 830 injection molded onto the substrate 838. Data pit pattern830 comprising a set of pits and lands is adjacent to, or a part of,substrate 838. Layer 826 is adjacent to the semi-reflective layer 822.Semi-reflective layer or coating 822 is adjacent and conforms to firstdata pit pattern 818 comprising a set of pits and lands. Data pit 818 isadjacent to or a part of the transparent cover layer 814.

[0111] As illustrated in FIG. 9, an optical beam source laser 850 isprovided, as is detector 852. Optical laser 850 emits an optical beamtowards layer 814 through an objective lens (not shown in FIG. 9). Aportion of the light emitted by laser 850 passes through a lens (notshown), the semi-reflective layer, or coating, 822 and is reflected byhighly reflective layer, or coating, 834 and sensed by detector 852,which senses modulations in light intensity based on the presence orabsence of a pit or land in a particular spot on the highly reflectivelayer or coating 822.

[0112] A portion of the optical beam emitted by optical laser 850 ispartially reflected by semi-reflective layer or coating 822 is sensed bydetector 852, which senses modulations in light intensity based on thepresence or absence of a pit or land in a particular spot onsemi-reflective layer or coating 822.

[0113] In one embodiment of the invention as illustrated in FIG. 10, anoptical storage device 910 of the Blu-ray rewritable type furthercomprises two read and rewritable layers 926, 954. Optical storagedevice 910 comprises a substrate layer 972 about 1.1 mm thick, adjacentto highly reflective layer or coating 968. Adjacent to layer or coating968 is a first dielectric layer 964 comprising ZnS—SiO₂, adjacent tolayer 964 is a first interface layer 960 such as Ge—N or others.Adjacent to layer 960 is a phase-change type recording layer such asGe—Sb—Te 954 and the like with thickness about 10 to 15 nm, adjacent tolayer 954 is layer 950 a second layer such as Ge—N and the like.Adjacent to layer 950 is layer 946 a second dielectric layer ofZnS—SiO₂. Optical storage device 910 further includes an intermediatelayer 942 sandwiched between the dielectric layer 946 approximately 20to 40 microns thick and a semi-reflective layer or coating 938 about 10nm thick. A third dielectric layer 934 comprised of ZnS—SiO₂ is adjacentto layer or coating 938. Adjacent to layer 934 is a third Interfacelayer 930 made with Ge—N or others, a recording layer 926 6-10 nm thickcomprised of Ge—Sn—Sb—Te or other phase-change material is sandwichedbetween layers 930 and a forth interface layer 922 made of Ge—N and thelike. Adjacent to layer 922 is a forth layer of dielectric materiallayer 918 comprised of ZnS—SiO₂ Adjacent to layer 918 is a transparentcover layer 914 about 80 to 100 microns thick.

[0114] As illustrated in FIG. 10 an optical beam emitted by laser 970passes through layers 914, 918, 922, 926, 930, 934 and is reflected bylayer 938 and sensed by detector 972. A portion of an optical beamemitted by laser 970 passes through layers 914, 918, 922, 926, 930, 934,938, 942, 946. 950, 954, 960, 964, and is reflected by layer 968 to andsensed by detector 972. All the silver alloy compositions disclosed inthis invention can be used for the semi-reflective layer 938 or thehighly reflective layer 968. In the recording mode, the laser beam fromlaser 970 will be focused on the phase-change layer 926 or 954 to changeits reflectivity properties similar to a conventional CD-RW, DVD−RW,DVD+RW or next generation of optical discs with playback laserwavelength at around 400 nm as disclosed in prior art such as U.S. Pat.Nos. 6,544,616, 6,652,948, 6,649,241 and others.

[0115] It is understood that the disc structure as described in FIG. 11can be modified that both 1014 and 1060 can be of approximately of thesame thickness or around 0.6 mm and with similar phase-change materialrecording stack, the disc structure could be a rewritable optical discof the “Advanced Optical Disc” or AOD type wherein the recording andplayback laser wavelength is around 400 nm.

[0116] It is further understood that all the optical disc structure asdescribed in FIG. 7, 8 , 9, 12 contain a dual layer disc structure ofthe prerecorded type wherein the playback laser beam has a wavelength ofaround 635 to 650 nm as in FIG.7 and 8, or contain a dual layer HD-DVDdisc structure wherein the playback laser has a wavelength around 400 nmor any other optical disc structure with two or more layers ofinformation all recorded or played back from one side of the disc inwhich a semi-reflective layer or layers of silver alloy as disclosed inthis invention is made useful.

[0117] One embodiment of the invention as illustrated in FIG. 11 is anoptical storage device 1010 of the ‘Blu-ray’configuration furthercomprising two write once layers 1048 and 1024. Optical storage device1010 is a dual-layer write once recording medium comprised of 1.1 mmthick substrate layer 1060, adjacent to a highly reflective layer 1056about 30 to 60 nm thick usually made with silver alloy of the currentinvention or an aluminum alloy. Layer 1056 is adjacent to protectivelayer 1052, layer 1052 is adjacent to a recordable layer 1048, 15 to 25nm thick comprised of Te—O—Pd based material or others. Layer 1048 isadjacent to protective film layer 1044.

[0118] Layer 1044 is adjacent to a separation layer or spacer layer 1040which is adjacent to a 10 nm thick semi-reflective layer or coating 1034made with silver alloy of the current invention. Layer or coating 1034is adjacent to protective film layer 1030 which is adjacent to a second10 nm thick recording layer 1024 comprising Te—O—Pd based material orothers. Layer 1024 is adjacent to protective film 1020 which is adjacentto a 0.075 mm thick cover layer 1014.

[0119] As illustrated in FIG. 11, an optical beam emitted by laser 1070passes a lens system with NA 0.85 (not shown in FIG. 11 through layers1014, 1020, 1024, 1030 and is reflected by the semi-reflective layer1034 and sensed by detector 1072. A portion of an optical beam emittedby laser 1070 passes through layers 1014, 1020, 1024, 1030, 1034, 1040,1044, 1048, 1052, and is reflected by highly reflective layer 1056 andsensed by detector 1072. Detector 1072 senses modulations in lightintensity based on the amorphous or the crystalline state of the layer1024 or 1048 in a particular spot on semi-reflective layer or coating1034 and on the highly reflective layer 1056 and reads the storedinformation back by focusing laser light from 1070 laser on thewrite-once layer 1024 or 1048. The spacer layer 1040 should be thickenough so that when the read beam is focused on the recordable layer1024, the read beam is sufficiently defocused on the next recordablelayer 1048 and only the modulation of light information from 1024 isreflected back to the detector 1072. Conversely, when the read beam isfocused on the recordable layer 1048, the read beam is sufficientlydefocused on the other recording layer 1024 and only the modulation from1048 is reflected to the detector 1072 and read.

[0120] It is also understood that as described in FIG. 10 and 11, a duallayer disc of the write-once or a rewritable type with a phase changerecording layer or other types of recording layers can be constructedthat at least two recording layers can be recorded and read from oneside or the same side of the disc wherein a semi-reflective layer madewith silver alloy of the current invention can be utilized and madeuseful.

[0121] Another embodiment the invention, as illustrated in FIG. 12 isoptical storage device 1110 of a prerecorded type is the proposed nextgeneration optical storage device sometimes referred to as an AdvancedOptical Device (AOD). AOD is a system that uses a 405 nm wavelengthlaser beam and a lens system with a NA of 0.65 to record and retrieveinformation for both faces of an optical storage device wherein thetransparent substrates 1120 and 1140 made typically with injectionmolded polycarbonate are approximately 0.6 mm thick.

[0122] Device 1110 comprises a transparent substrate layer 1140 adjacentto a highly-reflective layer or coating 1136 which is adjacent to andconforms to the contours of a first data pit pattern 1138 comprising aset of pits and lands. High reflectivity layer 1136 is adjacent tospacer layer 1132 which is adjacent to a semi-reflective layer orcoating 1124 of the current invention which is adjacent to and conformsto the contours of a second data pit pattern 1128 comprising a series ofpits and lands. Layer 1124 is adjacent to a second substrate or layer1120.

[0123] As illustrated in FIG. 12, a portion of an optical beam emittedby laser 1150 passes through layers 1120, 1124, 1128, 1132, and isreflected by the highly reflective layer 1136 and sensed by detector1152. A portion of an optical beam emitted by laser 1150 passes throughlayers 1120, and is reflected by semi-reflective layer or coating 1124and sensed by detector 1152. Detector 1152 senses modulations in lightintensity based on the presence or absence of a pit or land in aparticular spot on semi-reflective layer or coating 1124 and the highlyreflective layer or coating 1136 by focusing on layer 1124 or 1136.

[0124] In another embodiment the invention, illustrated in FIG. 13 anoptical storage device 1210 of the organic dye recordable-dual-layertype comprises two layers which are both readable and recordable fromthe same side of the device. Device 1210 comprises a transparentsubstrate layer 1214 adjacent to first recordable dye layer 1218. Dyelayer 1218 is adjacent to semi-reflective layer or coating 1222 of thecurrent invention. Layer or coating 1222, sometimes called “Layer zero”or L0, is adjacent to spacer layer 1226. Spacer layer 1226 is adjacentto a second dye recording layer 1230. Layer 1230 is adjacent to highlyreflective layer or coating 1234. Reflective layer or coating 1234,sometimes called “layer one” or L1, is adjacent to polycarbonatesubstrate or layer 1238.

[0125] In write mode, as illustrated in FIG. 13, optical beam source1250 emits a laser beam which passes through layers 1214, and is focusedon dye layer 1218. When laser 1250 is operating at high intensity theoptical beam focused on layer 1218 decomposes the dye in layer 1218creating a data pit pattern comprising the equivalent of a series ofpits and lands. A portion of an optical beam emitted by laser 1250passes through layers 1214, 1218, 1222, 1226 and is focused on dye layer1230. When laser 1250 is operating at high intensity, the optical beamfocused on layer 1230 decomposes the dye in layer 1230 to create a datapit pattern comprising a series of pits and lands.

[0126] In read mode a portion of an optical beam emitted by laser 1250passes through transparent polycarbonate layer 1214 and dye layer 1218,is reflected by the semi-reflective layer or coating 1222 and sensed bydetector 1252. A portion of the optical beam also passes through layers1214, 1218, 1222, 1226, 1230 and is reflected by highly reflective layer1234 and sensed by detector 1252. Detector 1252 senses modulations inlight intensity based on the presence or absence of a pit or land in aparticular spot on the reflective layer or coating 1234 or by thesemi-reflective layer or coating 1222 depending on whether the laserlight 1250 is focused on the semi-reflective layer 1222 or the highlyreflective layer 1234. For the general operation of an organic dye-basedoptical recording medium, the reader can refer to U.S. Pat. Nos.6,641,889, 6,551,682, etc.

[0127] It is further understood that the optical disc structure asdescribed in FIG. 13 can be a dual layer DVD-R or DVD+R disc wherein theplayback laser beam has a wavelength of around 635 to 650 nm, or thestructure can be a dual layer HD-DVD-R disc wherein the playback laserhas a wavelength around 400 nm or any other optical disc structurewherein two or more layers of information can all be recorded or playedback from one side of the disc in which a semi-reflective layer orlayers of silver alloy as disclosed in this invention is made useful.

[0128] As used herein, the term “reflectivity” refers to the fraction ofoptical power incident upon transparent substrate 14, 114, 214, 314, 414or 514 which, when focused to a spot on a region of layer 20, 120, 216,220, 316, 320, 324, 422 or 522 could in principle, be sensed by aphotodetector in an optical readout device. It is assumed that thereadout device includes a laser, an appropriately designed optical path,and a photodetector, or the functional equivalents thereof.

[0129] This invention is based on the inventor's discovery that, aparticular silver-based alloy provides sufficient reflectivity andcorrosion resistance to be used as the reflective or the semi-reflectivelayer in an optical storage medium, without the inherent cost of agold-based alloy or the process complication of a silicon-basedmaterial. In one embodiment, silver is alloyed with a comparativelysmall amount of zinc. In this embodiment, the relationship between theamounts of zinc and silver ranges from about 0.01 a/o percent (atomicpercent) to about 15 a/o percent zinc and from about 85 a/o percent toabout 99.99 a/o percent silver. But preferably in respect to each metal,the alloy has from about 0.1 a/o percent to about 10.0 a/o percent zincand from about 90.0 a/o percent to about 99.9 a/o percent silver.

[0130] In another embodiment, the silver is alloyed with a comparativelysmall amount of aluminum. In this embodiment, the relationship betweenthe amounts of aluminum and silver ranges from about 0.01 a/o percent(atomic percent) to about 5 a/o percent aluminum and from about 95 a/opercent to about 99.99 a/o percent silver. But preferably in respect toeach metal, the alloy has from about 0.1 a/o percent to about 3.0a/opercent aluminum and from about 97 a/o percent to about 99.9a/o percentsilver.

[0131] In another embodiment of the present invention, the silver-based,binary alloy systems as mentioned above are further alloyed with cadmium(Cd), lithium (Li), or manganese (Mn). If one or more of these metalsreplaces a portion of the silver in the alloy, the corrosion resistanceof the resultant thin film will likely increase; however, thereflectivity will also likely decrease. The amount of cadmium, lithium,or manganese that may favorably replace some of the silver in the binaryalloy ranges from; about 0.01 a/o percent to about 20 a/o percent of theamount of silver present for cadmium; from about 0.01 a/o percent toabout 10 a/o percent, or even, to about 15 a/o percent of the amount ofsilver present for lithium; and from about 0.01 a/o percent to about 7.5a/o percent of the amount of silver present for manganese.

[0132] In still another embodiment of the present invention, thesilver-based, zinc and aluminum binary alloy systems as mentioned aboveare further alloyed with a precious metal such as gold (Au), rhodium(Rh), copper (Cu), ruthenium (Ru), osmium (Os), iridium (Ir), platinum(Pt), palladium (Pd), and mixtures thereof, which may be added to theabove binary alloys with the preferable range of precious metal to beabout 0.01 a/o to 5.0 a/o percent of the amount of silver present. Inaddition to precious metals, the above alloys may be still furtheralloyed with a metal such as titanium (Ti), nickel (Ni), indium (In),chromium (Cr), germanium (Ge), tin (Sn), antimony (Sb), gallium (Ga),silicon (Si), boron (B), zirconium (Zr), molybdenum (Mo), and mixturesthereof. In relation to the amount of silver that is present in theaforementioned silver alloys, the amount of these metals that maypreferably be added ranges from about 0.01 a/o percent to about 5.0 a/oof the amount of silver present.

[0133] In another embodiment, silver is alloyed with at least one otherelement, selected from the group of elements including copper, silicon,cadmium, tin, lithium, nickel, cobalt, indium, chromium, antimony,gallium, boron, molybdenum, zirconium, beryllium, titanium andmagnesium, wherein said other elements are present from about 0.01 a/opercent to 10.0 a/o percent of the amount of silver present. In onepreferred embodiment, the non-silver element is present in the alloy inthe amount of about 0.1 a/o percent to 5.0 a/o percent.

[0134] In still another embodiment, the silver is alloyed with acomparatively small amount of both zinc and aluminum. In thisembodiment, the relationship between the amounts of zinc, aluminum andsilver ranges from about 0.1 a/o percent to about 15 a/o percent zinc,from about 0.1 a/o percent to about 5 a/o percent aluminum, and fromabout 80 a/o percent to about 99.8 a/o percent silver. But preferablywith respect to each metal, the alloy has from about 0.1 a/o percent toabout 5.0 a/o percent zinc, from about 0.1 a/o percent to about 3.0 a/opercent aluminum, and from about 92.0 a/o percent to about 99.8 a/opercent silver.

[0135] In yet another embodiment of the present invention, thesilver-based zinc-aluminum ternary alloy system as mentioned above isfurther alloyed with a fourth metal. The fourth metal may includemanganese or nickel. If one or a mixture of these metals replaces aportion of the silver in the alloy, the corrosion resistance of theresultant thin film will likely increase; however, the reflectivity willalso likely decrease. The amount of manganese or nickel that mayfavorably replace some of the silver in the above ternary alloys rangesfrom, about 0.01 a/o percent to about 7.5 a/o percent of the amount ofsilver present for manganese, with a preferable range being betweenabout 0.01 a/o percent and about 5.0 a/o percent of the amount of silverpresent. The amount of nickel may range from between about 0.01 a/opercent to about 5.0 a/o percent of the amount of silver present with apreferable range being between from about 0.01 a/o percent and about 3.0a/o percent of the amount of silver present.

[0136] In still another embodiment of the present invention, thesilver-based zinc-aluminum ternary alloy system as mentioned above isfurther alloyed with a precious metal such as gold, rhodium, copper,ruthenium, osmium, iridium, platinum, palladium, and mixtures thereof,which may be added to the above ternary alloys with the preferable rangeof precious metal to be about 0.01 a/o to 5.0 a/o percent of the amountof silver present. In addition to the precious metals, the above alloysmay also be alloyed with a metal such as titanium, nickel, indium,chromium, germanium, tin, antimony, gallium, silicon, boron, zirconium,molybdenum, and mixtures thereof. In relation to the amount of silverthat is present in the above silver alloy system, the amount of suchmetals that may be preferably added ranges from about 0.01 a/o percentto about 5.0 a/o percent of the amount of silver present.

[0137] In another embodiment, the silver is alloyed with a comparativelysmall amount of manganese. In this embodiment, the relationship betweenthe amounts of manganese and silver ranges from about 0.01 a/o percentto about 7.5 a/o percent manganese and from about 92.5 a/o percent toabout 99.99 a/o percent silver. But preferably, in respect to eachmetal, the alloy has from about 0.1 a/o percent to about 5 a/o percentmanganese and from about 95 a/o percent to about 99.9 a/o percentsilver.

[0138] In yet another embodiment of the present invention, thesilver-based binary manganese alloy system as mentioned above is furtheralloyed with a third metal. The third metal may include cadmium, nickel,lithium and mixtures thereof. If one or a mixture of these metalsreplaces a portion of the silver in the alloy, the corrosion resistanceof the resultant thin film will likely increase; however, thereflectivity will also likely decrease. In relation to the amount ofsilver that is present in the above binary alloy systems, the amount ofcadmium may be range from about 0.01 a/o percent to about 20 a/o percentof the alloy of the amount of silver present, the amount of nickel mayrange from between about 0.01 a/o percent to about 5.0 a/o percent ofthe amount of silver present, and the amount of lithium may range fromabout 0.01 a/o percent to about 10.0 a/o percent of the amount of silverpresent.

[0139] In still another embodiment of the present invention, theaforementioned silver-based manganese alloy system is further alloyedwith a precious metal such as gold, rhodium, copper, ruthenium, osmium,iridium, platinum, palladium, and mixtures thereof, which may be addedto these binary alloys, the preferred range of precious metal added isabout 0.01 a/o to 5.0 a/o percent of the amount of silver present. Inaddition to the precious metals, the aforementioned alloys may also bealloyed with a metal such as titanium, indium, chromium, germanium, tin,antimony, gallium, silicon, boron, zirconium, molybdenum, and mixturesthereof. In relation to the amount of silver that is present in theabove silver alloy system, the amount of the latter metal(s) that maypreferably be added ranges from about 0.01 a/o percent to about 5.0 a/opercent of the amount of silver present.

[0140] In still another embodiment, silver is alloyed with acomparatively small amount of germanium. In this embodiment, therelationship between the amounts of germanium and silver ranges fromabout 0.01 a/o percent to about 3.0 a/o percent germanium and from about97.0 a/o percent to about 99.99 a/o percent silver. But preferably inrespect to each metal, the alloy has from about 0.1 a/o percent to about1.5 a/o percent germanium and from about 98.5 a/o percent to about 99.9a/o percent silver.

[0141] In yet another embodiment of the present invention, thesilver-based germanium alloy system as mentioned above is furtheralloyed with a third metal. The third metal may include manganese oraluminum. If one or a mixture of these metals replaces a portion of thesilver in the alloy, the corrosion resistance of the resultant thin filmwill likely increase; however, the reflectivity will also likely drop.In relation to the amount of silver that is present in the above binaryalloy system, the amount of manganese may be range from about 0.01 a/opercent to about 7.5 a/o percent of the amount of silver present and theamount of aluminum may range from between about 0.01 a/o percent toabout 5.0 a/o percent of the amount of silver present.

[0142] In still another embodiment of the present invention, theaforementioned silver-based germanium alloy system is further alloyedwith a precious metal such as gold, rhodium, copper, ruthenium, osmium,iridium, platinum, palladium, and mixtures thereof, which may be addedto the above binary alloys, the preferable range of precious metalsadded is about 0.01 a/o to 5.0 a/o percent of the amount of silverpresent. In addition to the precious metals, the alloys may also bealloyed with a metal such as zinc, cadmium, lithium, nickel, titanium,zirconium, indium, chromium, tin, antimony, gallium, silicon, boron,molybdenum, and mixtures thereof. In relation to the amount of silverpresent in the above silver alloy system, the amount of these metalsthat may be preferably added ranges from about 0.01 a/o percent to about5.0 a/o percent of the amount of silver present.

[0143] In still another embodiment, the silver is alloyed with acomparatively small amount of both copper and manganese. In thisembodiment, the relationship between the amounts of copper, manganeseand silver ranges from about 0.01 a/o percent to about 10 a/o percentcopper, from about 0.01 a/o percent to about 7.5 a/o percent manganese,and from about 82.5 a/o percent to about 99.98 a/o percent silver. Butpreferably in respect to each metal, the alloy has from about 0.1 a/opercent to about 5.0 a/o percent copper, from about 0.1 a/o percent toabout 3.0 a/o percent manganese, and from about 92.0 a/o percent toabout 99.8 a/o percent silver.

[0144] In yet another embodiment of the present invention, thesilver-based copper-manganese alloy system as mentioned above is furtheralloyed a fourth metal. The fourth metal such as aluminum, titanium,zirconium, nickel, indium, chromium, germanium, tin, antimony, gallium,silicon, boron, molybdenum, and mixtures thereof. In relation to theamount of silver that is present in the above silver alloy system, theamount of fourth metal that may be preferably added ranges from about0.01 a/o percent to about 5.0 a/o percent of the amount of silverpresent.

[0145] The optical properties of these silver alloys as thin film, witha thickness in the range of 8 to 12 nanometers, for the semi reflectivelayer of DVD-9 dual layer discs are illustrated in Table I in thefollowing. As mentioned in U.S. Pat. No. 5,464,619 assigned toMatsushita Electric and U.S. Pat. No. 5,726,970 assigned to Sony, in adual layer optical disc structure (as illustrated in FIG. 3 and in TableI), the relationship between R₀ the reflectivity of Layer “0”or 216 andR₁ the reflectivity of Layer “1”or 220 is given by R₀=R₁T₀ ². Where thereflectivity of Layer “1” or 220 is measured from outside the disc, andthe transmission of Layer “0” is given as T₀. When the thickness oflayer “0”is optimized for balanced signal and reflectivity, and Layer“1” is an conventional aluminum alloy, at 50 to 60 nanometers, thebalanced reflectivity of various silver alloys is shown in Table I. InTable I, R is the reflectivity of the thin film achievable at athickness of 60 nanometer or greater, at a wavelength of 650 nanometerif used as Layer “1” or the high reflectivity layer of DVD-9 or anyother high reflectivity application in an optical information storagemedium. All compositions in the table I are given in atomic percent.TABLE I Balance of reflectivity of Layer 0 and Layer 1 of DVD-9 duallayer disc for various silver alloy Layer 0 and typical aluminum alloyLayer 1. Composition T₀ R₀ R₁ R Ag—13.0% Zn 0.47 0.185 0.183 0.80Ag—6.0% Zn 0.52 0.22 0.224 0.92 Ag—4.0% Zn 0.53 0.23 0.233 0.93 Ag—10.3%Cd 0.51 0.22 0.216 0.91 Ag—14.5% Li 0.53 0.23 0.232 0.93 Ag—4.3% Al 0.470.18 0.183 0.80 Ag—1.5% Al 0.53 0.23 0.234 0.93 Ag—2.0% Ni 0.54 0.2410.241 0.94 Ag—1.0% Ni 0.545 0.247 0.246 0.95 Ag—3.1% Mn 0.51 0.216 0.2140.91 Ag—1.5% Mn 0.54 0.243 0.242 0.94 Ag—0.4% Ti 0.49 0.198 0.197 0.88Ag—1.0% Zr 0.52 0.229 0.224 0.93

[0146] In still another embodiment of the present invention, thesputtering target and the thin film on the optical information storagemedium is a silver alloy with a comparatively small addition of aluminumas an alloying element. In this embodiment, the relationship between theamounts of silver and aluminum ranges from about 0.01 a/o percent toabout 5.0 a/o percent aluminum and from about 95.0 a/o percent to about99.99 a/o percent silver. But preferably from about 0.1 a/o percent toabout 3.0 a/o percent aluminum, and from about 97.0 a/o percent to about99.9 a/o percent silver. This silver and aluminum binary alloy can befurther alloyed with zinc, cadmium, lithium, manganese, nickel, titaniumand zirconium or mixtures of these metals. In relation to the amount ofsilver that is present in the above silver and aluminum binary alloy,the amount of the above-identified metal that may be preferably addedranges from 0.01 a/o percent to about 5.0 a/o percent of the silvercontent.

[0147] For the convenience of the reader, the following are somecombinations of silver alloys, wherein the alloying elements, which maybe preferably alloyed with silver, are identified by their periodictable symbols: Ag+Zn, or Ag+Cd, or Ag+Li, or Ag+Al, or Ag+Ni, or Ag+Mn,or Ag+Ti, or Ag+Zr, or Ag+Pd+Zn, or Ag+Pt+Zn, or Ag+Pd+Mn, or Ag+Pt+Mn,or Ag+Zn+Li, or Ag+Pt+Li, or Ag+Li+Mn, or Ag+Li+Al, or Ag+Ti+Zn, orAg+Zr+Ni, or Ag+Al+Ti, or Ag+Pd+Ti or Ag+Pt+Ti, or Ag+Ni+Al, orAg+Mn+Ti, or Ag+Zn+Zr, or Ag+Li+Zr, or Ag+Mn+Zn, or Ag+Mn+Cu, orAg+Pd+Pt+Zn or Ag+Pd+Zn+Mn, or Ag+Zn+Mn+Li, or Ag+Cd+Mn+Li, orAg+Pt+Zn+Li, or Ag+Al+Ni+Zn, or Ag+Al+Ni+Ti, or Ag+Zr+Ti+Cd, orAg+Zr+Ni+Li, or Ag+Zr+Ni+Al, or Ag+Pt+Al+Ni, or Ag+Pd+Zn+Al, orAg+Zr+Zn+Ti, or Ag+Ti+Ni+Al.

[0148] In another embodiment of the present invention, silver can bealloyed additionally with indium, chromium, nickel, germanium, tin,antimony, gallium, silicon, boron, zirconium, and molybdenum or mixtureof these elements. In relation to the amount of silver that is presentin the alloy systems, the amount of the above-identified elements thatmay be added ranges from about 0.01 a/o percent to about 5.0 a/o percentof the silver content. But more preferably, the amount of alloyingelements added to silver may range from about 0.1 a/o percent to about3.0 a/o percent. This is further illustrated in Table II for an opticalinformation storage medium as presented in FIG. 3. All the opticalproperty symbols in Table II have the same meaning as the same symbolsas those used in Table I. TABLE II Balance of reflectivity of Layer 0and Layer 1 of DVD-9 dual layer disc for various silver alloy Layer 0and typical aluminum alloy Layer 1. Composition T₀ R₀ R₁ R Ag—2.5% In0.500 0.212 0.208 0.91 Ag—1.2% Cr 0.535 0.243 0.238 0.94 Ag—0.7% Ge0.515 0.220 0.220 0.92 Ag—1.0% Sn 0.504 0.216 0.211 0.92 Ag—0.5% Sb0.520 0.224 0.224 0.93 Ag—3.0% Ga 0.475 0.195 0.187 0.86 Ag—1.5% Si0.490 0.202 0.199 0.90 Ag—1.2% B 0.513 0.247 0.218 0.92 Ag—0.8% Mo 0.5150.220 0.218 0.92

[0149] It is well understood in the art, that the compositions listed inTable I and Table II can also be used as the high reflectivity layer(Layer 1) in prerecorded dual layer optical disc structures such asDVD-9, DVD-14 or DVD-18, in a tri-layer optical disc structure asillustrated in FIG. 4, in a recordable optical disc such as DVD-R, in arewritable optical disc such as DVD-RAM, or DVD-RW, or as the oneillustrated in FIG. 5.

[0150] For the convenience of the reader, the following are some silveralloys, where the alloying elements, that may preferably be alloyed withsilver are identified by their periodic table symbols; Ag+In, or Ag+Cr,or Ag+Ge, or Ag+Sn, or Ag+Sb, or Ag+Ga, or Ag+Si, or Ag+B, or Ag+Mo, orAg+In+Cr, or Ag+Cr+Ge, or Ag+Cr+Sn, or Ag+Cr+Sb, or Ag+Cr+Si, orAg+Si+In, or Ag+Si+Sb, or Ag+Si+B, or Ag+Si+Mo, or Ag+Mo+In, orAg+Mo+Sn, or Ag+Mo+B, or Ag+Mo+Sb, or Ag+Ge+B, or Ag+In+Cr+Ge, orAg+Cr+Sn+Sb, or Ag+Ga+Si+Mo, or Ag+Cr+Si+Mo, or Ag+B+Mo+Cr, orAg+In+Sb+B, or Ag+Cr+Si+B, Ag+Ga+Ge+Cr, or Ag+Si+Ge+Mo or Ag+Sb+Si+B, orAg+Cr+Si+In, or Ag+Si+Cr+Sn.

[0151] The optical properties of a few of the ternary silver alloys ofthe present invention are further illustrated in Table III. In TableIII, which shows the reflectivity and transmission of a thin film, layerzero, with a thickness of about 8 to 12 nm, in a DVD-9 dual layer discconstruction. The meaning of each symbol is the same as in Table I.TABLE III Balance of reflectivity of Layer 0 and Layer 1 of DVD-9 duallayer disc for various ternary silver alloy layer 0 and typical aluminumalloy Layer 1. Composition T₀ R₀ R₁ R Ag—1.2% Pd—1.4% Zn 0.54 0.2450.242 0.95 Ag—0.8% Cu—1.5% Mn 0.535 0.240 0.238 0.94 Ag—1.5% Al—1.0% Mn0.50 0.213 0.208 0.91 Ag—1.0% Cu—0.3% Ti 0.50 0.210 0.207 0.90 Ag—1.2%Al—1.3% Zn 0.53 0.224 0.233 0.93 Ag—1.0% Ge—0.7% Al 0.49 0.203 0.2010.89 Ag—1.2% Sb—0.3% Li 0.47 0.187 0.183 0.83

[0152] In another embodiment of the current invention, the thin film onan optical information storage medium is, silver alloyed with acomparatively small amount of at least one other element selected fromthe group consisting of copper, silicon, cadmium, tin, lithium, nickel,cobalt, indium, chromium, antimony, gallium, boron, molybdenum,zirconium, beryllium, titanium and magnesium. The amount of otherelements that may be alloyed with silver ranges from about 0.01 a/opercent to about 10.0 a/o percent. And more preferably, the amount ofthe other element present in the silver based alloy ranges from about0.1 a/o percent to about 5.0 a/o percent, of the amount of silverpresent.

[0153] In another embodiment of the current invention, the thin film onan optical information storage medium is, silver alloyed with copper andzinc. The amount of Cu present in the alloy ranges from about 0.01 a/opercent to about 10.0 a/o percent; and the amount of zinc present rangesfrom about 0.01 a/o percent to about 10.0 a/o percent, of the silverpresent in the alloy.

[0154] In another embodiment of the current invention, the thin film onan optical information storage medium is, silver alloyed with copper andtitanium. The amount of Cu present in the alloy ranges from about 0.01a/o percent to about 10.0 a/o percent; and the amount of titaniumpresent in the alloy ranges from about 0.01 a/o percent to about 5.0 a/opercent, of the amount of silver present.

[0155] In another embodiment of the current invention, the thin film onan optical information storage medium is, silver alloyed with at leastone other metal selected from the group including gold, rhodium,ruthenium, osmium, iridium, platinum, palladium, and mixtures thereof.The amount of the other metal present in the silver based alloy rangesfrom about 0.01 a/o percent to about 5.0 a/o percent of the amount ofsilver present.

[0156] In another embodiment of the current invention, the thin film onan optical information storage medium is, silver alloyed with copper,and silicon. The amount of copper in the alloy ranges from about 0.01a/o to about 10.0 a/o percent, of the amount of silver present in thealloy. The amount of silicon present in the alloy ranges from about 0.01a/o to about 5.0 a/o percent of the amount of silver present.

[0157] In still another embodiment of the current invention, the thinfilm on an optical information storage medium is, silver alloyed with atleast one of the following elements selected from the group including;copper, zinc, titanium, cadmium, lithium, nickel, cobalt, indium,aluminum, germanium, chromium, germanium, tin, beryllium, magnesium,manganese, antimony, gallium, silicon, boron, zirconium, molybdenum, andmixtures thereof. The amount of the elements alloyed with silver rangesfrom about, 0.01 a/o percent to about 10.0 a/o percent of the amount ofsilver present. In one preferred embodiment the amount of the otherelement alloyed with silver ranges from about 0.1 a/o to about 5.0 a/opercent of the amount of silver present.

[0158] In another embodiment of the current invention, the thin film onan optical information storage medium is, silver alloyed with copper andzinc. The amount of copper in the alloy ranges from about 0.01 a/o toabout 10.0 a/o percent, of the amount of silver present in the alloy.And the amount of zinc in the alloy ranges from about 0.01 a/o to about10.0 a/o percent, of the amount of silver present in the alloy.

[0159] In still another embodiment of the current invention, the thinfilm on an optical information storage medium is, silver alloyed with atleast one element selected from the group including gold, rhodium,ruthenium, osmium, iridium, platinum, palladium, and mixtures thereof.The amount of the element present in the alloy ranges from about 0.01a/o to about 5.0 a/o percent, of the amount of silver present in thealloy.

[0160] In yet another embodiment of invention, the thin film on anoptical information storage medium is a silver copper alloy defined byAg_(x)Cu_(y). The amount of silver present in the alloy is given by avalue of x, where x is in the range of about 0.90 to about 0.999. Andthe amount of Cu in the alloy is given by a value of y, and y is in therange of about 0.001 to about 0.01.

[0161] In one preferred embodiment of the invention, the amount ofsilver in the alloy is given by a value of x in the range of about 0.95to about 0.999, and the amount of Cu in the alloy is given by a value ofy, in the range of about 0.001 to about 0.050.

[0162] In yet another embodiment of the current invention, the thin filmon an optical information storage medium is, silver alloyed with copper,and at least one other element selected from the group includingsilicon, cadmium, tin, lithium, nickel, cobalt, indium, chromium,antimony, gallium, boron, molybdenum, zirconium, beryllium, titanium,magnesium. The amount of the other elements present in the alloy rangesfrom 0.01 a/o percent to about 10.0 a/o percent, of the amount of silverpresent.

[0163] In still another embodiment of the current invention, the thinfilm on an optical information storage medium is silver alloyed withcopper and manganese. The amount of copper in the alloy ranges fromabout 0.001 to about 0.01 a/o; the amount of manganese present in thealloy ranges from about 0.01 a/o to about 7.5 a/o percent, of the amountof silver present. In another preferred embodiment of the invention theamount of manganese present in the alloy ranges from about 1.01 a/o toabout 5.0 a/o percent, of the amount of silver present.

[0164] In another embodiment of the current invention, the thin film onan optical information storage medium is, silver alloyed with copper andtitanium. The amount of copper present in the alloy ranges from about0.001 to about 0.01 a/o, and the amount of titanium present in the alloyranges from about 0.01 a/o to about 5.0 a/o percent, of the amount ofsilver present.

[0165] In still another embodiment of the current invention, the thinfilm on an optical information storage medium is, silver alloyed withcopper and silicon. The amount of copper in the alloy is in the range ofabout 0.001 to about 0.01 a/o, and the amount of silicon in the alloyranges from about 0.01 a/o to about 5.0 a/o percent, of the amount ofsilver present.

[0166] In still another embodiment of the current invention, thesputtering target and the thin film on an optical information storagemedium is, silver alloyed with a comparatively, small amount of copperand other elements selected from the group consisting of: aluminum,nickel, manganese, titanium, zirconium, indium, chromium, germanium,tin, antimony, gallium, silicon, boron, molybdenum and mixtures thereof.In this embodiment, the relationship between the amounts of silver andcopper ranges from about 0.01 a/o percent to about 5.0 a/o percentcopper and from about 95.0 a/o percent to about 99.99 a/o percentsilver. But preferably from about 0.1 a/o percent to about 3.0 a/opercent copper, and from about 97.0 a/o percent to about 99.9 a/opercent silver. In relationship to the amount of silver that is presentin the alloy system, the amount of the above-identified elements thatmay be added ranges from 0.01 a/o percent to about 5.0% of the silvercontent. But more preferably, the amount of alloying elements added tosilver may ranges from about 0.1 a/o percent to about 3.0 a/o percent.As data presented in Table I, II and III indicated, if the individualalloy addition to silver is more than 5.0 a/o percent, the balancedreflectivity between layer zero and layer one in the DVD-9 dual layerdisc structure is likely to be lower than the DVD specification of 18percent, therefore not composition with utility.

[0167] Having presented the preceding compositions for the thin filmmaterials, it is important to recognize that both the manufacturingprocess of the sputtering target and the process to deposit the targetmaterial into a thin film play important roles in determining the finalproperties of the film. To this end, a preferred method of making thesputtering target will now be described. In general, vacuum melting andcasting of the alloys or melting and casting under protectiveatmosphere, are preferred to minimize the introduction of other unwantedimpurities.

[0168] Afterwards, the as-cast ingot should undergo a cold or hotworking process to break down the segregated and the nonuniform as-castmicrostructure. One preferred method is cold or hot forging or cold orhot uniaxial compression with a more than 50 percent of size reduction,followed by annealing to recrystallize the deformed material into fineequi-axed grain structure with preferred texture of<1,1,0>orientation.This texture promotes directional sputtering in a sputtering apparatusso that more of the atoms from the sputtering target will be depositedonto the disc substrates for more efficient use of the target material.

[0169] Alternatively, a cold or hot multi-directional rolling processwith more than a 50 percent size reduction can be employed, followed byannealing, to promote a random oriented microstructure in the targetfollowed by machining the target to a final shape and size suitable fora given sputtering apparatus. A target, with a more random crystalorientation, will ejection atoms more randomly during sputtering, andwill produce a disc substrate with a more uniform distribution andthickness.

[0170] Depending on the application, different discs' optical and othersystem requirements, either a cold or hot forging or a cold or hotmulti-directional rolling process can be employed in the targetmanufacturing process to optimize, the optical and other performancerequirements of, the thin film for use in a given application.

[0171] The alloys of this invention can be deposited using thewell-known methods described earlier including, for example sputtering,thermal evaporation or physical vapor deposition, and possiblyelectrolytic or electroless plating processes. The thin film alloy'sreflectivity can vary depending on the method of application. Anyapplication method that adds impurities to, or changes the surfacemorphology of, the thin film layer on the disc could conceivably, lowerthe reflectivity of the layer. But to a first order of approximation,the reflectivity of the thin film layer on the optical disc is primarilydetermined by the starting material of the sputtering target,evaporation source material, or the purity and composition of theelectrolytic and electroless plating chemicals used.

[0172] It should be understood that the reflective layer of thisinvention can be used for future generations of optical discs that use areading laser of a shorter wavelength, for example, a reading laser witha wavelength of 650 nanometers or shorter.

[0173] It should also be understood that, if the reflective film isreduced to a thickness of approximately 5 to 20 nanometers, asemi-reflective film layer can be formed from the alloys of thisinvention that have sufficient light transmittance for use in dual-layerDVD or dual layer blue-ray optical disc applications.

EXAMPLES Example 1

[0174] A silver based alloy with about 1.2 atomic percent chromium andapproximately 1.0 atomic percent zinc, at a thickness of about 60-100nanometers, will have a reflectivity of approximately 94 to 95 percentat a wavelength of 800 nanometers and a reflectivity of approximately 93to 94 percent at a wavelength of 650 nanometers and a reflectivity ofapproximately 86 to 88 percent at a wavelength of 400 nanometers.

Example 2

[0175] A silver-rich alloy with 1.5 a/o percent of manganese, and 0.8a/o percent of copper will have a reflectivity of approximately 94 to 95percent at 650 nanometers wavelength. If the thickness of the thin filmis reduced to the 8 to 12 nanometers range, the reflectivity will bereduced to the range of 18 to 30 percent applicable for use as a DVD-9'ssemi-reflective layer. Adding a low concentration of deoxidizer such aslithium can further simplify the manufacturing process of the startingmaterial of the thin film. As silver has a tendency to dissolve someoxygen in the solid state, which tends to lower the reflectivity of thealloy, the added lithium will react with the oxygen and lessen thedegree of oxygen's impact to reflectivity. The desirable range oflithium is in the approximate range of 0.01 percent to 5.0 atomicpercent, with the preferred range from about 0.1 to 1.0 a/o percent.

Example 3

[0176] A silver based alloy with about 0.5 a/o percent of nickel andabout 0.5 a/o percent of zinc, about 60-70 nanometers thick, will have areflectivity of approximately 95 percent at a wavelength of about 650nanometers. It is suitable for any high reflectivity application in anoptical information storage medium.

Example 4

[0177] A silver based alloy. sputtering target with a composition ofabout 1.0 a/o percent manganese, 0.3 a/o percent titanium and thebalance silver is employed to produce the semi-reflective layer of aDVD-9 dual layer disc using the following procedure. On top of atransparent polycarbonate half disc approximately 0.6 millimeters thickand 12 centimeter in diameter with information pits injection moldedfrom a suitable stamper, a semi-reflective thin film or layer “zero” ofsilver based alloy approximately 10 to 11 nanometers thick is depositedor coated, in a magnetron sputtering machine. On top of anothertransparent polycarbonate half disc approximately 0.6 millimeter thickwith information pits injection molded from a suitable stamper, a highreflectivity thin film or layer “one” of and aluminum based alloyapproximately 55 nanometers thick is deposited using a suitable aluminumsputtering target in a sputtering machine. These two half discs are thenseparately spin-coated with suitable liquid organic resins, bondedtogether with layer “zero” and layer “one” facing each other and theresin is cured with ultraviolet light. The distance within the discbetween the layer “zero” and the layer “one” is kept at about 55+/−5microns.

[0178] The reflectivity of the two information layers is measured fromthe same side of the disc and found to be about the same 21 percentusing a 650 nanometers wavelength laser light. Electronic signals suchas jitter and PI error are measured and found to be within published DVDspecifications. Subsequently, an accelerated aging test at 80 degrees Cand 85 percent relative humidity for 4 days is conducted on the disc.Afterwards, the reflectivity and the electronic signals are measuredagain and no significant changes are observed as compared to the samemeasurements made before the aging test.

Example 5

[0179] A silver alloy sputtering target with the composition in atomicpercent of about 0.2 percent lithium, 1.0 percent manganese, 0.3 percentgermanium and the balance silver is employed to produced thesemi-reflective layer of a DVD-9 dual layer disc. The procedure used tomake the discs is the same as the procedure used in the aforementionedexample 4. The reflectivity of the two information layers in thefinished disc is measured from the same side of the disc and found to beabout the same, about 22.5 percent using a 650 nanometers wavelengthlaser light. Electronic signals such as jitter and PI error are alsomeasured and found to be within published DVD specifications.Subsequently, an accelerated aging test at 70 degrees C. and 50 percentrelative humidity for 96 hours is conducted on the disc. Afterwards, thereflectivity and the electronic signals are measured again and nosignificant changes are observed compared to the same measurements madebefore the aging test.

[0180] It is understood that the same silver alloy thin film in thisexample, deposited on the disc with a thickness ranging from about 30 toabout 200 nanometers range can serve as the high reflectivity layer,such as Layer “one”in DVD-9 or Layer “two” in a tri-layer optical disc,as illustrated in FIG. 4. The same silver alloy can serve in other highreflectivity applications such as a rewritable optical disc such asDVD-RW, DVD-RAM in a general structure as illustrated in FIG. 5 at 650nanometers wavelength or any other future optical information storagemedium played back at around 400 nanometers wavelength.

Example 6

[0181] A silver based alloy sputtering target with a composition in a/o% of approximately 1.0% copper, 1.0% zinc, and the balance silver isused to produce the reflective layer of another type of recordable disca DVD−R disc or a DVD+R disc using the following procedure. Referringnow to FIG. 2. An azo based recording dye is spin-coated on top of atransparent polycarbonate half disc about 0.6 mm thick and 12 cm indiameter with pregrooves suitable for DVD−R or DVD+R injection molded bya suitable stamper, and, dried. Subsequently, a reflective layer ofsilver based alloy approximately 150 nm in thickness is deposited orcoated on the recording dye using the sputtering target with theaforementioned composition in a magnetron sputtering machine.Afterwards, this half disc is bonded to another 0.6 mm thickness halfdisc using a UV cured resin. Information is recorded onto the disc in aDVD−R or DVD+R recorder and the quality of the electronic signal ismeasured.

[0182] The disc is then subjected to an accelerated aging test. The discis held at 80 degrees C. and 85% RH for 96 hours. Afterwards, thereflectivity and the electronic signals are measured again and nosignificant changes are observed as compared to the same measurementsbefore aging test.

Example 7

[0183] A process to make the sputtering target with the composition asindicated in example 6 is described hereafter. Suitable charges ofsilver, manganese and aluminum are put into the crucible of a suitablevacuum induction furnace. The vacuum furnace is pumped down to vacuumpressure of approximately 1 milli-torr and then induction heating isused to heat the charge. While the charge is heating up and theout-gassing finished, the furnace can be back filled with argon gas to apressure of about 0.2 to 0.4 atmosphere. Casting of the liquid melt canbe accomplished at a temperature approximately 10% above the meltingpoint of the charge. The graphite crucible holding the melt can beequipped with a graphite stopper at the bottom of the crucible.

[0184] Pouring of the molten metal into individual molds of eachsputtering target can be accomplished by opening, and closing, thegraphite stopper in synchrony with mechanically placing each mold intoposition just underneath the melting crucible to that the proper amountof melt is poured and cast into each mold. Afterwards, additional argonflow into the vacuum furnace can be introduced to cool and quench thecasting. Subsequently, a cold or warm multi-directional rolling processthat causes a more than 50% reduction in thickness can be used to breakup any nonuniform casting microstructure.

[0185] Then the final anneal is done at 550 to 600 degrees C. in aprotective atmosphere for 15 to 30 minutes. After being machined intothe right shape and size, cleaned in detergent and properly dried, thefinished sputtering target is ready to be put into a magnetronsputtering apparatus to coat optical discs. Approximate sputteringparameters sufficient to make the semi-reflective layer of an ultra highdensity optical disc suitable for use with a playback laser with awavelength of 400 nanometers as mentioned in example 9 are as follows: 1kilowatt of sputtering power, 1 second of sputtering time, an argonpartial pressure of 1 to 3 milli-torr, with a target to disc distance ofapproximately 4 to 6 centimeters, giving a deposition rate of 10nanometers per second. Using the same sputtering target and sputteringapparatus, the high reflectivity layer can be made with about the samesputtering parameters as the semi-reflective layer, except that todeposit the high reflectivity layer the sputtering power needs to beincreased to 4 to 5 kilowatts. Thus an ultra high density read-onlyoptical disc, 5 inches in diameter, with user storage capacity of about20 to 25 giga bytes or higher per side can be made in this manner. Adual layer disc with the structure, illustrated in FIG. 3, has thecapacity to store approximately 40 to 50 giga bytes of information, morethan enough storage capacity for a full-length motion picture in thehigh-definition digital television format.

Example 8

[0186] The feasibility of using the same silver alloy thin film for boththe reflective layer and the semi-reflective layer of a dual layer ultrahigh density read-only optical disc with a playback laser at awavelength of 400 nanomaters is investigated.

[0187] A silver alloy sputtering target with a composition given in a/o%: of Pd, 1.2%, Zn, 1.4% and balance silver was used to produce a duallayer optical information storage medium as depicted in FIG. 3. A thinfilm about 10 nanometers thick of this silver alloy was deposited on asuitable polycarbonate substrate by using a magnetron sputteringmachine. Referring now to FIG. 3, the indices of refraction (n) of thetransparent substrate 214, the semi-reflective layer 216, the spacerlayer 218 and the high reflectivity layer are 1.605, 0.035, 1.52, 0.035,respectively. The extinction coefficient (k) for the semi-reflectivelayer and the high reflectivity layer is 2.0.

[0188] Calculations show that with a thickness of 24 nm, thesemi-reflective layer will have a reflectivity R₀ of 0.242 and atransmission T₀ of 0.600 in the disc at a wavelength of 400 nm. At athickness of 55 nm, the high reflectivity layer will have a reflectivityR₁ of 0.685. The reflectivity of the high reflectivity layer measuredfrom outside the disc through the semi-reflective layer will be R₀=R₁T₀² or 0.247. In other words, to the detector outside the disc, thereflectivity from both the semi-reflective layer and the highreflectivity layer will be approximately the same. This fulfills oneimportant requirement for a dual layered optical information storagemedium, that the reflectivity from these 2 information layers beapproximately equal, the relationship between the optical properties ofthese two layers is R₀=R₁T₀ ².

Example 9

[0189] The same silver alloy used in example 8 can also be used as thehigh reflectivity layer and the two semi-reflective layers in atri-layer optical information storage medium for at playback using alaser with a wavelength of 400 nm. Referring now to FIG. 4. Calculationsshow that, at a thickness of 16 nm for the first semi-reflective layer316, a thickness of 24 nm for the second semi-reflective layer 320, anda thickness of 50 nm for the high reflectivity layer 324, thereflectivity, measured at the detector 332, will be 0.132, 0.137, 0.131,respectively. This shows that approximately the same reflectivity can beachieved from all three layers. Balance of reflectivity from all three,information layers can be achieved, using the same silver alloy.Additionally, one sputtering machine and one silver alloy sputteringtarget can be used to manufacture all three layers of an ultra highdensity tri-layer optical information storage medium suitable for usewith playback laser at wavelength 400 nm in a production environment. Itwill also be obvious, that aluminum alloys can also be used for the highreflectivity layer of this tri-layer medium.

Example 10

[0190] A silver alloy sputtering target having the composition given ina/o % of: Pd, 0.4%; Cu, 1.5%; and balance silver was used to produce thereflective layer in a rewritable phase change disc structure such asDVD+RW, DVD−RW or DVD−RAM. Referring to FIG. 5. Successive layers ofZnO.SiO₂, Ag—In—Sb—Te, and ZnO.SiO₂ of suitable thickness are coated ona 0.6 mm thick polycarbonate substrate which has continuous spiraltracks of grooves and lands made by injection molding from a suitablestamper. Next, a sputtering target with the aforementioned compositionis used in a magnetron sputtering apparatus to deposit a silver alloyfilm about 150 nm thick on top of the ZnO.SiO₂ film. Subsequently, thehalf disc is bonded with a suitable adhesive to the another 0.6 mm thickhalf disc of the same construction as the aforementioned half disc toform a complete disc.

[0191] Repeated record and erase cycles are performed in a suitableDVD+RW, DVD−RW or DVD−RAM drive. The disc meets the performancerequirements imposed on the recording medium. The disc further undergoes an accelerated environmental test at 80 degrees C., 85% relativehumidity for 4 days. Afterwards, disc performance is checked again, nosignificant change in the disc property is observed as compared to thedisc's performance before the environmental test.

Example 11

[0192] A silver alloy sputtering target having the composition given ina/o % of: Mn,0.7%; Cu, 1.5%; Ti,0.2% and balance silver was used toproduce the semi-reflective layer 938 approximately 10 nm in thicknessin a Blu-Ray rewritable phase change dual-layer disc structure such asthe one described in FIG. 10. Successive layers of silver alloy 60 nm inthickness, dielectric layer of ZnO.SiO₂, interface layer, recordinglayer such as Ge—Sb—Te, another interface layer and dielectric layerZnO.SiO₂ of suitable thickness are coated on a 1.1 mm thickpolycarbonate substrate which has continuous spiral tracks of groovesand lands made by injection molding from a suitable stamper. Afterwards,an organic resin about 50 microns in thickness as a spacer layer isspin-coated on the 1.1 mm thick substrate and cured by UV light. Next,another sputtering target with the aforementioned composition is used ina magnetron sputtering apparatus to deposit the semi-reflective silveralloy film about 10 nm thick on top of the spacer layer, followed bysputtered coating of ZnO.Sio₂ dielectric film, interface layer, phasechange recording layer, interface layer and dielectric layer.Subsequently, the film or layer stacks on the 1.1 mm thickness substrateis spin-coated and UV cured a cover layer about 100 microns in thicknessto form a complete disc.

[0193] Repeated record and erase cycles are performed in a suitableBlu-Ray recorder drive with playback lens NA of 0.85 and focused laserbeam of 405 nm wavelength. The disc meets the performance requirementsimposed on the recording medium. The disc further under goes anaccelerated environmental test at 75 degrees C., 85% relative humidityfor 10 days. Afterwards, disc performance is checked again, nosignificant change in the disc property is observed as compared to thedisc's performance before the environmental test.

Example 12

[0194] A silver alloy sputtering target having a composition given ina/o % of: Cu, 1.0%; Ag, 99.0% was used to produce the highly reflectivelayer in a rewritable phase change disc structure or “DVR” as shown inFIG. 6. In this DVR structure, between dielectric layer 520 and highlyreflective layer 522, there is an interface layer of SiC (not shown).The layers in this example are deposited in the reverse order from theorder of layer addition used in Example 10. The transparent substrate524 was made of polycarbonate and injection molded from a suitablestamper, then the silver alloy reflective layer was deposited on thetransparent substrate using the above-mentioned sputtering target in amagnetron sputtering apparatus. Dielectric layer 520 (preferablyZnO.SiO₂), recording layer 518 (preferably Ag—In—Sb—Te), anotherdielectric layer 516 (preferably ZnO.SiO₂) and an interface layer(preferably SiC) were then vacuum coated, in sequence. Finally, the discwas covered with a layer of UV cured resin 514, about 100 microns thick.

[0195] The performance of the disc is verified with a DVR type recordingand play back system using a 405 nm wavelength laser beam. Repeatedrecord and erase cycles are conducted satisfactorily. The disc issubjected to an accelerated environmental test at 80 degrees C. and 85%relative humidity for 4 days. The performance of the disc is againchecked and verified. No significant degradation of the disc's propertyis observed.

Example 13

[0196] A silver based alloy sputtering target with a composition in a/o% of approximately 2.2% copper, 0.5% zinc, and the balance silver isused to produce the semi-reflective layer or L0 of another type ofrecordable disc such as a DVD−R dual-layer disc or a DVD+R dual-layerdisc as shown in FIG. 13 using the following procedure. An azo basedrecording dye is spin-coated on top of a transparent polycarbonate halfdisc about 0.6 mm thick and 12 cm in diameter with pregrooves suitablefor DVD−R dual-layer or DVD+R dual-layer injection molded by a suitablestamper, and, dried. Subsequently, a semi-reflective layer of silverbased alloy approximately 10 nm in thickness is deposited or coated onthe recording dye using the sputtering target with the aforementionedcomposition in a magnetron sputtering machine. Afterwards, this halfdisc is bonded to the other 0.6 mm thickness half disc using a UV curedresin. The other half disc contains 150 nm thickness of silver alloysputtered from another sputtering target of the composition: 1.7 a/o %Cu, 1.0 a/o % Zn and 97.3 a/o % Ag on the clear polycarbonate substrateand subsequently coated with another Azo based recording dye and driedby hot circulating air. Information is recorded onto both layers of thedisc in a DVD−R dual-layer or DVD+R dual-layer recorder and the qualityof the electronic signal is measured. The disc is then subjected to anaccelerated aging test at 80 degrees C. and 85% RH for 2 days.Afterwards, the reflectivity and the electronic signals of the disc aremeasured again and no significant changes are observed as compared tothe same measurements before the aging test.

THE CLAIMS

[0197] While the invention has been illustrated and described in detail,this is to be considered as illustrative and not restrictive of thepatent rights. The reader should understand that only the preferredembodiments have been presented and all changes and modifications thatcome within the spirit of the invention are included if the followingclaims or the legal equivalent of these claims describes them.

I claim:
 1. An optical storage medium, comprising: a first layer havinga first pattern of features in at least one major surface; asemi-reflective layer, the semi-reflective layer including a metalalloy, said metal alloy including silver and copper, wherein therelationship between the amounts of silver and copper in the metal alloyis defined by Ag_(x)Cu_(y) where 0.90<x<0.9999 and 0.0001<y<0.10; asecond layer having a second pattern of features in at least one majorsurface; and a high reflective layer.
 2. The optical storage medium ofclaim 1, further comprising an optically recordable dye layer adjacentsaid semi-reflective layer.
 3. The optical storage medium of claim 2,wherein the first pattern of features includes a spiral groove.
 4. Theoptical storage medium of claim 1, wherein 0.001<y<0.05.
 5. The opticalstorage medium of claim 1, wherein said metal alloy further includeselement A, wherein element A is selected from the group of elementsconsisting of cadmium, lithium, indium, chromium, antimony, gallium,germanium, boron, molybdenum, zirconium, and beryllium, and wherein therelationship between the amounts of silver and element A in the metalalloy is defined by Ag_(x)A_(y) wherein 0.9999<x<0.9, 0.0001<y<0.1. 6.The optical storage medium of claim 1, further comprising: a third layeradjacent said semi-reflective layer, said third layer including adielectric material; a fourth layer, said fourth layer including anoptically re-recordable material; and a fifth layer, said fifth layerincluding a dielectric material.
 7. The optical storage medium of claim6, wherein the first pattern of features includes a spiral groove. 8.The optical storage medium of claim 6, wherein said opticallyre-recordable material is a phase-changeable material.
 9. The opticalstorage medium of claim 8, wherein said optically re-recordable materialfurther comprises a phase changeable material selected from the groupconsisting of Ge—Sb—Te, As—In—Sb—Te, Cr—Ge—Sb—Te, As—Te—Ge, Te—Ge—Sn,Te—Ge—Sn—O, Te—Se, Sn—Te—Se, Te—Ge—Sn—Au, Ge—Sb—Te, Sb—Te—Se, In—Se—Tl,In Sb, In—Sb—Se, In—Se—Tl—Co, Bi—Ge, Bi—Ge—Sb, Bi—Ge—Te, and Si—Te—Sn.10. The optical storage medium of claim 6, wherein said opticallyre-recordable material is a magneto-optic material.
 11. The opticalstorage medium of claim 10, wherein said optically re-recordablematerial further comprises a magneto-optic material selected from thegroup consisting of Tb—Fe—Co and Gd—Tb—Fe.
 12. An optical storagemedium, comprising: a first layer having a first pattern of features inat least one major surface; a semi-reflective layer, the semi-reflectivelayer including a metal alloy, said metal alloy including silver andzinc, wherein the relationship between the amounts of silver and zinc inthe metal alloy is defined by Ag_(x)Zn_(y) where 0.85<x<0.9999 and0.0001<y<0.15; a second layer having a second pattern of features in atleast one major surface; and a high reflective layer.
 13. The opticalstorage medium of claim 12, further comprising an optically recordabledye layer adjacent said semi-reflective layer.
 14. The optical storagemedium of claim 13, wherein the first pattern of features includes aspiral groove.
 15. The optical storage medium of claim 12, wherein0.001<y<0.05.
 16. The optical storage medium of claim 12, furthercomprising: a third layer adjacent said semi-reflective layer, saidthird layer including a dielectric material; a fourth layer, said fourthlayer including an optically re-recordable material; and a fifth layer,said fifth layer including a dielectric material.
 17. The opticalstorage medium of claim 16, wherein the first pattern of featuresincludes a spiral groove.
 18. The optical storage medium of claim 16,wherein said optically re-recordable material is a phase-changeablematerial.
 19. The optical storage medium of claim 18, wherein saidoptically re-recordable material further comprises a phase changeablematerial selected from the group consisting of Ge—Sb—Te, As—In—Sb—Te,Cr—Ge—Sb—Te, As—Te—Ge, Te—Ge—Sn, Te—Ge—Sn—O, Te—Se, Sn—Te—Se,Te—Ge—Sn—Au, Ge—Sb—Te, Sb—Te—Se, In—Se—Tl, In Sb, In—Sb—Se, In—Se—Tl—Co,Bi—Ge, Bi—Ge—Sb, Bi—Ge—Te, and Si—Te—Sn.
 20. The optical storage mediumof claim 16, wherein said optically re-recordable material is amagneto-optic material.
 21. The optical storage medium of claim 20,wherein said optically re-recordable material further comprises amagneto-optic material selected from the group consisting of Tb—Fe—Coand Gd—Tb—Fe.
 22. An optical storage medium, comprising: a first layerhaving a first pattern of features in at least one major surface; asemi-reflective layer, the semi-reflective layer including a metalalloy, said metal alloy including silver and manganese, wherein therelationship between the amounts of silver and manganese in the metalalloy is defined by Ag_(x)Mn_(y) where 0.90<x<0.9999 and 0.0001<y<0.10;a second layer having a second pattern of features in at least one majorsurface; and a high reflective layer.
 23. The optical storage medium ofclaim 22, further comprising an optically recordable dye layer adjacentsaid semi-reflective layer.
 24. The optical storage medium of claim 23,wherein the first pattern of features includes a spiral groove.
 25. Theoptical storage medium of claim 22, wherein 0.001<y<0.05.
 26. Theoptical storage medium of claim 22, further comprising: a third layeradjacent said semi-reflective layer, said third layer including adielectric material; a fourth layer, said fourth layer including anoptically re-recordable material; and a fifth layer, said fifth layerincluding a dielectric material.
 27. The optical storage medium of claim26, wherein the first pattern of features includes a spiral groove. 28.The optical storage medium of claim 26, wherein said opticallyre-recordable material is a phase-changeable material.
 29. The opticalstorage medium of claim 28, wherein said optically re-recordablematerial further comprises a phase changeable material selected from thegroup consisting of Ge—Sb—Te, As—In—Sb—Te, Cr—Ge—Sb—Te, As—Te—Ge,Te—Ge—Sn, Te—Ge—Sn—O, Te—Se, Sn—Te—Se, Te—Ge—Sn—Au, Ge—Sb—Te, Sb—Te—Se,In—Se—Tl, In Sb, In—Sb—Se, In—Se—Tl—Co, Bi—Ge, Bi—Ge—Sb, Bi—Ge—Te, andSi—Te—Sn.
 30. The optical storage medium of claim 26, wherein saidoptically re-recordable material is a magneto-optic material.
 31. Theoptical storage medium of claim 30, wherein said optically re-recordablematerial further comprises a magneto-optic material selected from thegroup consisting of Tb—Fe—Co and Gd—Tb—Fe.
 32. An optical storagemedium, comprising: a first layer having a first pattern of features inat least one major surface; a semi-reflective layer, the semi-reflectivelayer including a metal alloy, said metal alloy including silver andtitanium, wherein the relationship between the amounts of silver andtitanium in the metal alloy is defined by Ag_(x)Ti_(y) where0.95<x<0.9999 and 0.0001<y<0.05; a second layer having a second patternof features in at least one major surface; and a high reflective layer.33. The optical storage medium of claim 32, further comprising anoptically recordable dye layer adjacent said semi-reflective layer. 34.The optical storage medium of claim 33, wherein the first pattern offeatures includes a spiral groove.
 35. The optical storage medium ofclaim 32, wherein 0.001<y<0.03.
 36. The optical storage medium of claim32, further comprising: a third layer adjacent said semi-reflectivelayer, said third layer including a dielectric material; a fourth layer,said fourth layer including an optically re-recordable material; and afifth layer, said fifth layer including a dielectric material.
 37. Theoptical storage medium of claim 36, wherein the first pattern offeatures includes a spiral groove.
 38. The optical storage medium ofclaim 36, wherein said optically re-recordable material is aphase-changeable material.
 39. The optical storage medium of claim 38,wherein said optically re-recordable material further comprises a phasechangeable material selected from the group consisting of Ge—Sb—Te,As—In—Sb—Te, Cr—Ge—Sb—Te, As—Te—Ge, Te—Ge—Sn, Te—Ge—Sn—O, Te—Se,Sn—Te—Se, Te—Ge—Sn—Au, Ge—Sb—Te, Sb—Te—Se, In—Se—Tl, In Sb, In—Sb—Se,In—Se—Tl—Co, Bi—Ge, Bi—Ge—Sb, Bi—Ge—Te, and Si—Te—Sn.
 40. The opticalstorage medium of claim 36, wherein said optically re-recordablematerial is a magneto-optic material.
 41. The optical storage medium ofclaim 40, wherein said optically re-recordable material furthercomprises a magneto-optic material selected from the group consisting ofTb—Fe—Co and Gd—Tb—Fe.
 42. An optical storage medium, comprising: afirst layer having a first pattern of features in at least one majorsurface; a semi-reflective layer, the semi-reflective layer including ametal alloy, said metal alloy including silver and nickel, wherein therelationship between the amounts of silver and nickel in the metal alloyis defined by Ag_(x)Ni_(y) where 0.95<x<0.9999 and 0.0001<y<0.05; asecond layer having a second pattern of features in at least one majorsurface; and a high reflective layer.
 43. The optical storage medium ofclaim 42, further comprising an optically recordable dye layer adjacentsaid semi-reflective layer.
 44. The optical storage medium of claim 43,wherein the first pattern of features includes a spiral groove.
 45. Theoptical storage medium of claim 42, wherein 0.001<y<0.03.
 46. Theoptical storage medium of claim 42, further comprising: a third layeradjacent said semi-reflective layer, said third layer including adielectric material; a fourth layer, said fourth layer including anoptically re-recordable material; and a fifth layer, said fifth layerincluding a dielectric material.
 47. The optical storage medium of claim46, wherein the first pattern of features includes a spiral groove. 48.The optical storage medium of claim 46, wherein said opticallyre-recordable material is a phase-changeable material.
 49. The opticalstorage medium of claim 48, wherein said optically re-recordablematerial further comprises a phase changeable material selected from thegroup consisting of Ge—Sb—Te, As—In—Sb—Te, Cr—Ge—Sb—Te, As—Te—Ge,Te—Ge—Sn, Te—Ge—Sn—O, Te—Se, Sn—Te—Se, Te—Ge—Sn—Au, Ge—Sb—Te, Sb—Te—Se,In—Se—Tl, In Sb, In—Sb—Se, In—Se—Tl—Co, Bi—Ge, Bi—Ge—Sb, Bi—Ge—Te, andSi—Te—Sn.
 50. The optical storage medium of claim 46, wherein saidoptically re-recordable material is a magneto-optic material.
 51. Theoptical storage medium of claim 50, wherein said optically re-recordablematerial further comprises a magneto-optic material selected from thegroup consisting of Tb—Fe—Co and Gd—Tb—Fe.
 52. An optical storagemedium, comprising: a first layer having a first pattern of features inat least one major surface; a semi-reflective layer, the semi-reflectivelayer including a metal alloy, said metal alloy including silver andtin, wherein the relationship between the amounts of silver and tin inthe metal alloy is defined by Ag_(x)Sn_(y) where 0.90<x<0.9999 and0.0001<y<0.10; a second layer having a second pattern of features in atleast one major surface; and a high reflective layer.
 53. The opticalstorage medium of claim 52, further comprising an optically recordabledye layer adjacent said semi-reflective layer.
 54. The optical storagemedium of claim 53, wherein the first pattern of features includes aspiral groove.
 55. The optical storage medium of claim 52, wherein0.001<y<0.05.
 56. The optical storage medium of claim 52, furthercomprising: a third layer adjacent said semi-reflective layer, saidthird layer including a dielectric material; a fourth layer, said fourthlayer including an optically re-recordable material; and a fifth layer,said fifth layer including a dielectric material.
 57. The opticalstorage medium of claim 56, wherein the first pattern of featuresincludes a spiral groove.
 58. The optical storage medium of claim 56,wherein said optically re-recordable material is a phase-changeablematerial.
 59. The optical storage medium of claim 58, wherein saidoptically re-recordable material further comprises a phase changeablematerial selected from the group consisting of Ge—Sb—Te, As—In—Sb—Te,Cr—Ge—Sb—Te, As—Te—Ge, Te—Ge—Sn, Te—Ge—Sn—O, Te—Se, Sn—Te—Se,Te—Ge—Sn—Au, Ge—Sb—Te, Sb—Te—Se, In—Se—Tl, In Sb, In—Sb—Se, In—Se—Tl—Co,Bi—Ge, Bi—Ge—Sb, Bi—Ge—Te, and Si—Te—Sn.
 60. The optical storage mediumof claim 56, wherein said optically re-recordable material is amagneto-optic material.
 61. The optical storage medium of claim 60,wherein said optically re-recordable material further comprises amagneto-optic material selected from the group consisting of Tb—Fe—Coand Gd—Tb—Fe.
 62. An optical storage medium, comprising: a first layerhaving a first pattern of features in at least one major surface; asemi-reflective layer, the semi-reflective layer including a metalalloy, said metal alloy including silver and silicon, wherein therelationship between the amounts of silver and silicon in the metalalloy is defined by Ag_(x)Si_(y) where 0.90<x<0.9999 and 0.0001<y<0.10;a second layer having a second pattern of features in at least one majorsurface; and a high reflective layer.
 63. The optical storage medium ofclaim 62, further comprising an optically recordable dye layer adjacentsaid semi-reflective layer.
 64. The optical storage medium of claim 63,wherein the first pattern of features includes a spiral groove.
 65. Theoptical storage medium of claim 62, wherein 0.001<y<0.05.
 66. Theoptical storage medium of claim 62, further comprising: a third layeradjacent said semi-reflective layer, said third layer including adielectric material; a fourth layer, said fourth layer including anoptically re-recordable material; and a fifth layer, said fifth layerincluding a dielectric material.
 67. The optical storage medium of claim66, wherein the first pattern of features includes a spiral groove. 68.The optical storage medium of claim 66, wherein said opticallyre-recordable material is a phase-changeable material.
 69. The opticalstorage medium of claim 68, wherein said optically re-recordablematerial further comprises a phase changeable material selected from thegroup consisting of Ge—Sb—Te, As—In—Sb—Te, Cr—Ge—Sb—Te, As—Te—Ge,Te—Ge—Sn, Te—Ge—Sn—O, Te—Se, Sn—Te—Se, Te—Ge—Sn—Au, Ge—Sb—Te, Sb—Te—Se,In—Se—Tl, In Sb, In—Sb—Se, In—Se—Tl—Co, Bi—Ge, Bi—Ge—Sb, Bi—Ge—Te, andSi—Te—Sn.
 70. The optical storage medium of claim 66, wherein saidoptically re-recordable material is a magneto-optic material.
 71. Theoptical storage medium of claim 70, wherein said optically re-recordablematerial further comprises a magneto-optic material selected from thegroup consisting of Tb—Fe—Co and Gd—Tb—Fe.
 72. An optical storagemedium, comprising: a first layer having a first pattern of features inat least one major surface; a semi-reflective layer, the semi-reflectivelayer including a metal alloy, said metal alloy including silver andaluminum, wherein the relationship between the amounts of silver andaluminum in the metal alloy is defined by Ag_(x)Al_(y) where0.90<x<0.9999 and 0.0001<y<0.10; a second layer having a second patternof features in at least one major surface; and a high reflective layer.73. The optical storage medium of claim 72, further comprising anoptically recordable dye layer adjacent said semi-reflective layer. 74.The optical storage medium of claim 73, wherein the first pattern offeatures includes a spiral groove.
 75. The optical storage medium ofclaim 72, wherein 0.001<y<0.05.
 76. The optical storage medium of claim72, further comprising: a third layer adjacent said semi-reflectivelayer, said third layer including a dielectric material; a fourth layer,said fourth layer including an optically re-recordable material; and afifth layer, said fifth layer including a dielectric material.
 77. Theoptical storage medium of claim 76, wherein the first pattern offeatures includes a spiral groove.
 78. The optical storage medium ofclaim 76, wherein said optically re-recordable material is aphase-changeable material.
 79. The optical storage medium of claim 78,wherein said optically re-recordable material further comprises a phasechangeable material selected from the group consisting of Ge—Sb—Te,As—In—Sb—Te, Cr—Ge—Sb—Te, As—Te—Ge, Te—Ge—Sn, Te—Ge—Sn—O, Te—Se,Sn—Te—Se, Te—Ge—Sn—Au, Ge—Sb—Te, Sb—Te—Se, In—Se—Tl, In Sb, In—Sb—Se,In—Se—Tl—Co, Bi—Ge, Bi—Ge—Sb, Bi—Ge—Te, and Si—Te—Sn.
 80. The opticalstorage medium of claim 76, wherein said optically re-recordablematerial is a magneto-optic material.
 81. The optical storage medium ofclaim 80, wherein said optically re-recordable material furthercomprises a magneto-optic material selected from the group consisting ofTb—Fe—Co and Gd—Tb—Fe.
 82. An optical storage medium, comprising: afirst layer having a first pattern of features in at least one majorsurface; a semi-reflective layer, the semi-reflective layer including ametal alloy, said metal alloy including silver and indium, wherein therelationship between the amounts of silver and indium in the metal alloyis defined by Ag_(x)In_(y) where 0.90<x<0.9999 and 0.0001<y<0.10; asecond layer having a second pattern of features in at least one majorsurface; and a high reflective layer.
 83. The optical storage medium ofclaim 82, further comprising an optically recordable dye layer adjacentsaid semi-reflective layer.
 84. The optical storage medium of claim 83,wherein the first pattern of features includes a spiral groove.
 85. Theoptical storage medium of claim 82, wherein 0.001<y<0.05.
 86. Theoptical storage medium of claim 82, further comprising: a third layeradjacent said semi-reflective layer, said third layer including adielectric material; a fourth layer, said fourth layer including anoptically re-recordable material; and a fifth layer, said fifth layerincluding a dielectric material.
 87. The optical storage medium of claim86, wherein the first pattern of features includes a spiral groove. 88.The optical storage medium of claim 86, wherein said opticallyre-recordable material is a phase-changeable material.
 89. The opticalstorage medium of claim 88, wherein said optically re-recordablematerial further comprises a phase changeable material selected from thegroup consisting of Ge—Sb—Te, As—In—Sb—Te, Cr—Ge—Sb—Te, As—Te—Ge,Te—Ge—Sn, Te—Ge—Sn—O, Te—Se, Sn—Te—Se, Te—Ge—Sn—Au, Ge—Sb—Te, Sb—Te—Se,In—Se—Tl, In Sb, In—Sb—Se, In—Se—Tl—Co, Bi—Ge, Bi—Ge—Sb, Bi—Ge—Te, andSi—Te—Sn.
 90. The optical storage medium of claim 86, wherein saidoptically re-recordable material is a magneto-optic material.
 91. Theoptical storage medium of claim 90, wherein said optically re-recordablematerial further comprises a magneto-optic material selected from thegroup consisting of Tb—Fe—Co and Gd—Tb—Fe.
 92. An optical storagemedium, comprising: a first layer having a first pattern of features inat least one major surface; a semi-reflective layer, the semi-reflectivelayer including a metal alloy, said metal alloy including silver, copperand zinc, wherein the relationship between the amounts of silver,copper, and zinc in the metal alloy is defined by Ag_(x)Cu_(w)Zn_(z)where 0.80<x<0.9998, 0.0001<w<0.10, 0.0001<z<0.10; a second layer havinga second pattern of features in at least one major surface; and a highreflective layer.
 93. The optical storage medium of claim 92, furthercomprising an optically recordable dye layer adjacent saidsemi-reflective layer.
 94. The optical storage medium of claim 93,wherein the first pattern of features includes a spiral groove.
 95. Theoptical storage medium of claim 92, further comprising: a third layeradjacent said semi-reflective layer, said third layer including adielectric material; a fourth layer, said fourth layer including anoptically re-recordable material; and a fifth layer, said fifth layerincluding a dielectric material.
 96. The optical storage medium of claim95, wherein the first pattern of features includes a spiral groove. 97.The optical storage medium of claim 95, wherein said opticallyre-recordable material is a phase-changeable material.
 98. The opticalstorage medium of claim 97, wherein said optically re-recordablematerial further comprises a phase changeable material selected from thegroup consisting of Ge—Sb—Te, As—In—Sb—Te, Cr—Ge—Sb—Te, As—Te—Ge,Te—Ge—Sn, Te—Ge—Sn—O, Te—Se, Sn—Te—Se, Te—Ge—Sn—Au, Ge—Sb—Te, Sb—Te—Se,In—Se—Tl, In Sb, In—Sb—Se, In—Se—Tl—Co, Bi—Ge, Bi—Ge—Sb, Bi—Ge—Te, andSi—Te—Sn.
 99. The optical storage medium of claim 95, wherein saidoptically re-recordable material is a magneto-optic material.
 100. Theoptical storage medium of claim 99, wherein said optically re-recordablematerial further comprises a magneto-optic material selected from thegroup consisting of Tb—Fe—Co and Gd—Tb—Fe.
 101. An optical storagemedium, comprising: a first layer having a first pattern of features inat least one major surface; a semi-reflective layer, the semi-reflectivelayer including a metal alloy, said metal alloy including silver; and anelement A, wherein element A is selected from the group consisting ofcadmium, germanium, lithium, cobalt, chromium, antimony, gallium, boron,molybdenum, zirconium, and beryllium and wherein the relationshipbetween the amounts of silver and element A defined by Ag_(x)A_(y) where0.90<x<0.9999 and 0.0001<y<0.10; a second layer having a second patternof features in at least one major surface; and a high reflective layer.102. The optical storage medium of claim 101, further comprising anoptically recordable dye layer adjacent said semi-reflective layer. 103.The optical storage medium of claim 102, wherein the first pattern offeatures includes a spiral groove.
 104. The optical storage medium ofclaim 101, wherein 0.001<y<0.05.
 105. The optical storage medium ofclaim 101, wherein said metal alloy includes element B, wherein elementB is selected from the group of elements consisting of gold, rhodium,ruthenium, osmium, iridium, platinum, and palladium and wherein therelationship between the amounts of silver and element B in the metalalloy is defined by Ag_(x)B_(v) wherein 0.09<x<0.0001 and 0.0001<v<0.05.106. The optical storage medium of claim 101, further comprising: athird layer adjacent said semi-reflective layer, said third layerincluding a dielectric material; a fourth layer, said fourth layerincluding an optically re-recordable material; and a fifth layer, saidfifth layer including a dielectric material.
 107. The optical storagemedium of claim 106, wherein the first pattern of features includes aspiral groove.
 108. The optical storage medium of claim 106, whereinsaid optically re-recordable material is a phase-changeable material.109. The optical storage medium of claim 108, wherein said opticallyre-recordable material further comprises a phase changeable materialselected from the group consisting of Ge—Sb—Te, As—In—Sb—Te,Cr—Ge—Sb—Te, As—Te—Ge, Te—Ge—Sn, Te—Ge—Sn—O, Te—Se, Sn—Te—Se,Te—Ge—Sn—Au, Ge—Sb—Te, Sb—Te—Se, In—Se—Tl, In Sb, In—Sb—Se, In—Se—Tl—Co,Bi—Ge, Bi—Ge—Sb, Bi—Ge—Te, and Si—Te—Sn.
 110. The optical storage mediumof claim 106, wherein said optically re-recordable material is amagneto-optic material.
 111. The optical storage medium of claim 110,wherein said optically re-recordable material further comprises amagneto-optic material selected from the group consisting of Tb—Fe—Coand Gd—Tb—Fe.
 112. An optical storage medium, comprising: a first layerhaving a first pattern of features in at least one major surface; asemi-reflective layer, the semi-reflective layer including a metalalloy, said metal alloy including silver, copper, and an element A,wherein element A is selected from the group of elements consisting oftitanium and silicon, and wherein the relationship between the amountsof silver, copper, and element A defined by Ag_(x)Cu_(w)A_(y) where0.85<x<0.9998, 0.0001<w<0.1, and 0.0001<y<0.05; a second layer having asecond pattern of features in at least one major surface; and a highreflective layer.
 113. The optical storage medium of claim 112, furthercomprising an optically recordable dye layer adjacent saidsemi-reflective layer.
 114. The optical storage medium of claim 112,wherein the first pattern of features includes a spiral groove.
 115. Theoptical storage medium of claim 112, further comprising: a third layeradjacent said semi-reflective layer, said third layer including adielectric material; a fourth layer, said fourth layer including anoptically re-recordable material; and a fifth layer, said fifth layerincluding a dielectric material.
 116. The optical storage medium ofclaim 115, wherein the first pattern of features includes a spiralgroove.
 117. The optical storage medium of claim 115, wherein saidoptically re-recordable material is a phase-changeable material. 118.The optical storage medium of claim 117, wherein said opticallyre-recordable material further comprises a phase changeable materialselected from the group consisting of Ge—Sb—Te, As—In—Sb—Te,Cr—Ge—Sb—Te, As—Te—Ge, Te—Ge—Sn, Te—Ge—Sn—O, Te—Se, Sn—Te—Se,Te—Ge—Sn—Au, Ge—Sb—Te, Sb—Te—Se, In—Se—Tl, In Sb, In—Sb—Se, In—Se—Tl—Co,Bi—Ge, Bi—Ge—Sb, Bi—Ge—Te, and Si—Te—Sn.
 119. The optical storage mediumof claim 115, wherein said optically re-recordable material is amagneto-optic material.
 120. The optical storage medium of claim 119,wherein said optically re-recordable material further comprises amagneto-optic material selected from the group consisting of Tb—Fe—Coand Gd—Tb—Fe.